Getting a map() to return a list in Python 3.x









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I'm trying to map a list into hex, and then use the list elsewhere. In python 2.6, this was easy:



A: Python 2.6:



>>> map(chr, [66, 53, 0, 94])
['B', '5', 'x00', '^']


However, in Python 3.1, the above returns a map object.



B: Python 3.1:



>>> map(chr, [66, 53, 0, 94])
<map object at 0x00AF5570>


How do I retrieve the mapped list (as in A above) on Python 3.x?



Alternatively, is there a better way of doing this? My initial list object has around 45 items and id like to convert them to hex.










share|improve this question



























    up vote
    386
    down vote

    favorite
    76












    I'm trying to map a list into hex, and then use the list elsewhere. In python 2.6, this was easy:



    A: Python 2.6:



    >>> map(chr, [66, 53, 0, 94])
    ['B', '5', 'x00', '^']


    However, in Python 3.1, the above returns a map object.



    B: Python 3.1:



    >>> map(chr, [66, 53, 0, 94])
    <map object at 0x00AF5570>


    How do I retrieve the mapped list (as in A above) on Python 3.x?



    Alternatively, is there a better way of doing this? My initial list object has around 45 items and id like to convert them to hex.










    share|improve this question

























      up vote
      386
      down vote

      favorite
      76









      up vote
      386
      down vote

      favorite
      76






      76





      I'm trying to map a list into hex, and then use the list elsewhere. In python 2.6, this was easy:



      A: Python 2.6:



      >>> map(chr, [66, 53, 0, 94])
      ['B', '5', 'x00', '^']


      However, in Python 3.1, the above returns a map object.



      B: Python 3.1:



      >>> map(chr, [66, 53, 0, 94])
      <map object at 0x00AF5570>


      How do I retrieve the mapped list (as in A above) on Python 3.x?



      Alternatively, is there a better way of doing this? My initial list object has around 45 items and id like to convert them to hex.










      share|improve this question















      I'm trying to map a list into hex, and then use the list elsewhere. In python 2.6, this was easy:



      A: Python 2.6:



      >>> map(chr, [66, 53, 0, 94])
      ['B', '5', 'x00', '^']


      However, in Python 3.1, the above returns a map object.



      B: Python 3.1:



      >>> map(chr, [66, 53, 0, 94])
      <map object at 0x00AF5570>


      How do I retrieve the mapped list (as in A above) on Python 3.x?



      Alternatively, is there a better way of doing this? My initial list object has around 45 items and id like to convert them to hex.







      python list python-3.x map-function






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Oct 13 at 20:37









      Simeon Leyzerzon

      13k42746




      13k42746










      asked Aug 20 '09 at 0:27









      mozami

      2,84131619




      2,84131619






















          9 Answers
          9






          active

          oldest

          votes

















          up vote
          588
          down vote



          accepted










          Do this:



          list(map(chr,[66,53,0,94]))


          In Python 3+, many processes that iterate over iterables return iterators themselves. In most cases, this ends up saving memory, and should make things go faster.



          If all you're going to do is iterate over this list eventually, there's no need to even convert it to a list, because you can still iterate over the map object like so:



          # Prints "ABCD"
          for ch in map(chr,[65,66,67,68]):
          print(ch)





          share|improve this answer


















          • 1




            Thank you for the great explanation!!
            – mozami
            Aug 20 '09 at 0:35






          • 13




            Of course, you can iterate over this, too: (chr(x) for x in [65,66,67,68]). It doesn't even need map.
            – hughdbrown
            Aug 20 '09 at 0:40










          • @hughdbrown The argument for using 3.1's map would be lazy evaluation when iterating on a complex function, large data sets, or streams.
            – Andrew Keeton
            Aug 20 '09 at 0:45






          • 16




            @Andrew actually Hugh is uing a generator comprehension which would do the same thing. Note the parentheses rather than square brackets.
            – Triptych
            Aug 20 '09 at 0:49






          • 5




            Alternate solution (faster for large inputs too) when the values are known to be ASCII/latin-1 is to do bulk conversions at the C layer: bytes(sequence_of_ints_in_range_0_to_256).decode('latin-1') which makes a str faster by avoiding Python function calls for each element in favor of a bulk conversion of all elements using only C level function calls. You can wrap the above in list if you really need a list of the individual characters, but since str is already an iterable of its own characters, the only reason you'd do so is if you need mutability.
            – ShadowRanger
            Jul 1 '16 at 1:52

















          up vote
          82
          down vote













          Why aren't you doing this:



          [chr(x) for x in [66,53,0,94]]


          It's called a list comprehension. You can find plenty of information on Google, but here's the link to the Python (2.6) documentation on list comprehensions. You might be more interested in the Python 3 documenation, though.






          share|improve this answer


















          • 8




            Yes to list comprehensions.
            – hughdbrown
            Aug 20 '09 at 0:29






          • 4




            Hmmmm. Maybe there needs to be a general posting on list comprehensions, generators, map(), zip(), and a lot of other speedy iteration goodness in python.
            – hughdbrown
            Aug 20 '09 at 0:55






          • 33




            I guess because it's more verbose, you have to write an extra variable (twice)... If the operation is more complex and you end up writing a lambda, or you need also to drop some elements, I think a comprehension is definitively better than a map+filter, but if you already have the function you want to apply, map is more succinct.
            – fortran
            Jun 25 '10 at 9:43






          • 1




            +1: Easier to read & allows you to use functions with many parameters
            – Le Droid
            Mar 6 '14 at 21:55










          • map(chr, [66,53,0,94]) is definitely more concise than [chr(x) for x in [66,53,0,94]].
            – Giorgio
            Oct 26 at 20:01

















          up vote
          63
          down vote













          New and neat in Python 3.5:



          [*map(chr, [66, 53, 0, 94])]


          Thanks to Additional Unpacking Generalizations



          UPDATE



          Always seeking for shorter ways, I discovered this one also works:



          *map(chr, [66, 53, 0, 94]),


          Unpacking works in tuples too. Note the comma at the end. This makes it a tuple of 1 element. That is, it's equivalent to (*map(chr, [66, 53, 0, 94]),)



          It's shorter by only one char from the version with the list-brackets, but, in my opinion, better to write, because you start right ahead with the asterisk - the expansion syntax, so I feel it's softer on the mind. :)






          share|improve this answer


















          • 10




            What's wrong with list()?
            – Quelklef
            Aug 12 '17 at 12:56






          • 8




            @Quelklef list() doesn't look as neat
            – Arijoon
            Sep 28 '17 at 13:15






          • 3




            @Quelklef: Also, the unpacking approach is trivially faster thanks to not needing to look up the list constructor and invoke general function call machinery. For a long input, it won't matter; for a short one, it can make a big difference. Using the above code with the input as a tuple so it's not repeatedly reconstructed, ipython microbenchmarks show the list() wrapping approach takes about 20% longer than unpacking. Mind you, in absolute terms, we're talking about 150 ns, which is trivial, but you get the idea.
            – ShadowRanger
            Nov 8 '17 at 4:41










          • What was wrong with the old map? Maybe with a new name (lmap?) if the new default is to return an iterator?
            – Giorgio
            Oct 26 at 20:04

















          up vote
          20
          down vote













          List-returning map function has the advantage of saving typing, especially during interactive sessions. You can define lmap function (on the analogy of python2's imap) that returns list:



          lmap = lambda func, *iterable: list(map(func, *iterable))


          Then calling lmap instead of map will do the job:
          lmap(str, x) is shorter by 5 characters (30% in this case) than list(map(str, x)) and is certainly shorter than [str(v) for v in x]. You may create similar functions for filter too.



          There was a comment to the original question:




          I would suggest a rename to Getting map() to return a list in Python 3.* as it applies to all Python3 versions. Is there a way to do this? – meawoppl Jan 24 at 17:58




          It is possible to do that, but it is a very bad idea. Just for fun, here's how you may (but should not) do it:



          __global_map = map #keep reference to the original map
          lmap = lambda func, *iterable: list(__global_map(func, *iterable)) # using "map" here will cause infinite recursion
          map = lmap
          x = [1, 2, 3]
          map(str, x) #test
          map = __global_map #restore the original map and don't do that again
          map(str, x) #iterator





          share|improve this answer





























            up vote
            11
            down vote













            I'm not familiar with Python 3.1, but will this work?



            [chr(x) for x in [66, 53, 0, 94]]





            share|improve this answer
















            • 1




              works perfectly.
              – ExceptionSlayer
              Apr 18 '16 at 9:52

















            up vote
            3
            down vote













            Converting my old comment for better visibility: For a "better way to do this" without map entirely, if your inputs are known to be ASCII ordinals, it's generally much faster to convert to bytes and decode, a la bytes(list_of_ordinals).decode('ascii'). That gets you a str of the values, but if you need a list for mutability or the like, you can just convert it (and it's still faster). For example, in ipython microbenchmarks converting 45 inputs:



            >>> %%timeit -r5 ordinals = list(range(45))
            ... list(map(chr, ordinals))
            ...
            3.91 µs ± 60.2 ns per loop (mean ± std. dev. of 5 runs, 100000 loops each)

            >>> %%timeit -r5 ordinals = list(range(45))
            ... [*map(chr, ordinals)]
            ...
            3.84 µs ± 219 ns per loop (mean ± std. dev. of 5 runs, 100000 loops each)

            >>> %%timeit -r5 ordinals = list(range(45))
            ... [*bytes(ordinals).decode('ascii')]
            ...
            1.43 µs ± 49.7 ns per loop (mean ± std. dev. of 5 runs, 1000000 loops each)

            >>> %%timeit -r5 ordinals = list(range(45))
            ... bytes(ordinals).decode('ascii')
            ...
            781 ns ± 15.9 ns per loop (mean ± std. dev. of 5 runs, 1000000 loops each)


            If you leave it as a str, it takes ~20% of the time of the fastest map solutions; even converting back to list it's still less than 40% of the fastest map solution. Bulk convert via bytes and bytes.decode then bulk converting back to list saves a lot of work, but as noted, only works if all your inputs are ASCII ordinals (or ordinals in some one byte per character locale specific encoding, e.g. latin-1).






            share|improve this answer



























              up vote
              0
              down vote













              list(map(chr, [66, 53, 0, 94]))



              map(func, *iterables) --> map object
              Make an iterator that computes the function using arguments from
              each of the iterables. Stops when the shortest iterable is exhausted.



              "Make an iterator"




              means it will return an iterator.




              "that computes the function using arguments from each of the iterables"




              means that the next() function of the iterator will take one value of each iterables and pass each of them to one positional parameter of the function.



              So you get an iterator from the map() funtion and jsut pass it to the list() builtin function or use list comprehensions.






              share|improve this answer



























                up vote
                0
                down vote













                In addition to above answers in Python 3, we may simply create a list of result values from a map as



                li = 
                for x in map(chr,[66,53,0,94]):
                li.append(x)

                print (li)
                >>>['B', '5', 'x00', '^']


                We may generalize by another example where I was struck, operations on map can also be handled in similar fashion like in regex problem, we can write function to obtain list of items to map and get result set at the same time. Ex.



                b = 'Strings: 1,072, Another String: 474 '
                li =
                for x in map(int,map(int, re.findall('d+', b))):
                li.append(x)

                print (li)
                >>>[1, 72, 474]





                share|improve this answer




















                • @miradulo I supposed in Python 2, a list was returned, but in Python 3, only type is returned and I just tried to give in same format. If you think its needless, there maybe people like me who can find it useful and thats why I added.
                  – Harry_pb
                  Jun 15 at 17:32






                • 1




                  When there is already a list comprehension, a list function, and an unpacking answer, an explicit for loop doesn’t add much IMHO.
                  – miradulo
                  Jun 15 at 20:04

















                up vote
                0
                down vote













                Using list comprehension in python and basic map function utility, one can do this also:



                chi = [x for x in map(chr,[66,53,0,94])]






                share|improve this answer






















                • chi list will be containing, the ASIC value of the given elements.
                  – darshan k s
                  Nov 11 at 17:01










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                9 Answers
                9






                active

                oldest

                votes








                9 Answers
                9






                active

                oldest

                votes









                active

                oldest

                votes






                active

                oldest

                votes








                up vote
                588
                down vote



                accepted










                Do this:



                list(map(chr,[66,53,0,94]))


                In Python 3+, many processes that iterate over iterables return iterators themselves. In most cases, this ends up saving memory, and should make things go faster.



                If all you're going to do is iterate over this list eventually, there's no need to even convert it to a list, because you can still iterate over the map object like so:



                # Prints "ABCD"
                for ch in map(chr,[65,66,67,68]):
                print(ch)





                share|improve this answer


















                • 1




                  Thank you for the great explanation!!
                  – mozami
                  Aug 20 '09 at 0:35






                • 13




                  Of course, you can iterate over this, too: (chr(x) for x in [65,66,67,68]). It doesn't even need map.
                  – hughdbrown
                  Aug 20 '09 at 0:40










                • @hughdbrown The argument for using 3.1's map would be lazy evaluation when iterating on a complex function, large data sets, or streams.
                  – Andrew Keeton
                  Aug 20 '09 at 0:45






                • 16




                  @Andrew actually Hugh is uing a generator comprehension which would do the same thing. Note the parentheses rather than square brackets.
                  – Triptych
                  Aug 20 '09 at 0:49






                • 5




                  Alternate solution (faster for large inputs too) when the values are known to be ASCII/latin-1 is to do bulk conversions at the C layer: bytes(sequence_of_ints_in_range_0_to_256).decode('latin-1') which makes a str faster by avoiding Python function calls for each element in favor of a bulk conversion of all elements using only C level function calls. You can wrap the above in list if you really need a list of the individual characters, but since str is already an iterable of its own characters, the only reason you'd do so is if you need mutability.
                  – ShadowRanger
                  Jul 1 '16 at 1:52














                up vote
                588
                down vote



                accepted










                Do this:



                list(map(chr,[66,53,0,94]))


                In Python 3+, many processes that iterate over iterables return iterators themselves. In most cases, this ends up saving memory, and should make things go faster.



                If all you're going to do is iterate over this list eventually, there's no need to even convert it to a list, because you can still iterate over the map object like so:



                # Prints "ABCD"
                for ch in map(chr,[65,66,67,68]):
                print(ch)





                share|improve this answer


















                • 1




                  Thank you for the great explanation!!
                  – mozami
                  Aug 20 '09 at 0:35






                • 13




                  Of course, you can iterate over this, too: (chr(x) for x in [65,66,67,68]). It doesn't even need map.
                  – hughdbrown
                  Aug 20 '09 at 0:40










                • @hughdbrown The argument for using 3.1's map would be lazy evaluation when iterating on a complex function, large data sets, or streams.
                  – Andrew Keeton
                  Aug 20 '09 at 0:45






                • 16




                  @Andrew actually Hugh is uing a generator comprehension which would do the same thing. Note the parentheses rather than square brackets.
                  – Triptych
                  Aug 20 '09 at 0:49






                • 5




                  Alternate solution (faster for large inputs too) when the values are known to be ASCII/latin-1 is to do bulk conversions at the C layer: bytes(sequence_of_ints_in_range_0_to_256).decode('latin-1') which makes a str faster by avoiding Python function calls for each element in favor of a bulk conversion of all elements using only C level function calls. You can wrap the above in list if you really need a list of the individual characters, but since str is already an iterable of its own characters, the only reason you'd do so is if you need mutability.
                  – ShadowRanger
                  Jul 1 '16 at 1:52












                up vote
                588
                down vote



                accepted







                up vote
                588
                down vote



                accepted






                Do this:



                list(map(chr,[66,53,0,94]))


                In Python 3+, many processes that iterate over iterables return iterators themselves. In most cases, this ends up saving memory, and should make things go faster.



                If all you're going to do is iterate over this list eventually, there's no need to even convert it to a list, because you can still iterate over the map object like so:



                # Prints "ABCD"
                for ch in map(chr,[65,66,67,68]):
                print(ch)





                share|improve this answer














                Do this:



                list(map(chr,[66,53,0,94]))


                In Python 3+, many processes that iterate over iterables return iterators themselves. In most cases, this ends up saving memory, and should make things go faster.



                If all you're going to do is iterate over this list eventually, there's no need to even convert it to a list, because you can still iterate over the map object like so:



                # Prints "ABCD"
                for ch in map(chr,[65,66,67,68]):
                print(ch)






                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Aug 20 '09 at 0:42

























                answered Aug 20 '09 at 0:28









                Triptych

                152k29134165




                152k29134165







                • 1




                  Thank you for the great explanation!!
                  – mozami
                  Aug 20 '09 at 0:35






                • 13




                  Of course, you can iterate over this, too: (chr(x) for x in [65,66,67,68]). It doesn't even need map.
                  – hughdbrown
                  Aug 20 '09 at 0:40










                • @hughdbrown The argument for using 3.1's map would be lazy evaluation when iterating on a complex function, large data sets, or streams.
                  – Andrew Keeton
                  Aug 20 '09 at 0:45






                • 16




                  @Andrew actually Hugh is uing a generator comprehension which would do the same thing. Note the parentheses rather than square brackets.
                  – Triptych
                  Aug 20 '09 at 0:49






                • 5




                  Alternate solution (faster for large inputs too) when the values are known to be ASCII/latin-1 is to do bulk conversions at the C layer: bytes(sequence_of_ints_in_range_0_to_256).decode('latin-1') which makes a str faster by avoiding Python function calls for each element in favor of a bulk conversion of all elements using only C level function calls. You can wrap the above in list if you really need a list of the individual characters, but since str is already an iterable of its own characters, the only reason you'd do so is if you need mutability.
                  – ShadowRanger
                  Jul 1 '16 at 1:52












                • 1




                  Thank you for the great explanation!!
                  – mozami
                  Aug 20 '09 at 0:35






                • 13




                  Of course, you can iterate over this, too: (chr(x) for x in [65,66,67,68]). It doesn't even need map.
                  – hughdbrown
                  Aug 20 '09 at 0:40










                • @hughdbrown The argument for using 3.1's map would be lazy evaluation when iterating on a complex function, large data sets, or streams.
                  – Andrew Keeton
                  Aug 20 '09 at 0:45






                • 16




                  @Andrew actually Hugh is uing a generator comprehension which would do the same thing. Note the parentheses rather than square brackets.
                  – Triptych
                  Aug 20 '09 at 0:49






                • 5




                  Alternate solution (faster for large inputs too) when the values are known to be ASCII/latin-1 is to do bulk conversions at the C layer: bytes(sequence_of_ints_in_range_0_to_256).decode('latin-1') which makes a str faster by avoiding Python function calls for each element in favor of a bulk conversion of all elements using only C level function calls. You can wrap the above in list if you really need a list of the individual characters, but since str is already an iterable of its own characters, the only reason you'd do so is if you need mutability.
                  – ShadowRanger
                  Jul 1 '16 at 1:52







                1




                1




                Thank you for the great explanation!!
                – mozami
                Aug 20 '09 at 0:35




                Thank you for the great explanation!!
                – mozami
                Aug 20 '09 at 0:35




                13




                13




                Of course, you can iterate over this, too: (chr(x) for x in [65,66,67,68]). It doesn't even need map.
                – hughdbrown
                Aug 20 '09 at 0:40




                Of course, you can iterate over this, too: (chr(x) for x in [65,66,67,68]). It doesn't even need map.
                – hughdbrown
                Aug 20 '09 at 0:40












                @hughdbrown The argument for using 3.1's map would be lazy evaluation when iterating on a complex function, large data sets, or streams.
                – Andrew Keeton
                Aug 20 '09 at 0:45




                @hughdbrown The argument for using 3.1's map would be lazy evaluation when iterating on a complex function, large data sets, or streams.
                – Andrew Keeton
                Aug 20 '09 at 0:45




                16




                16




                @Andrew actually Hugh is uing a generator comprehension which would do the same thing. Note the parentheses rather than square brackets.
                – Triptych
                Aug 20 '09 at 0:49




                @Andrew actually Hugh is uing a generator comprehension which would do the same thing. Note the parentheses rather than square brackets.
                – Triptych
                Aug 20 '09 at 0:49




                5




                5




                Alternate solution (faster for large inputs too) when the values are known to be ASCII/latin-1 is to do bulk conversions at the C layer: bytes(sequence_of_ints_in_range_0_to_256).decode('latin-1') which makes a str faster by avoiding Python function calls for each element in favor of a bulk conversion of all elements using only C level function calls. You can wrap the above in list if you really need a list of the individual characters, but since str is already an iterable of its own characters, the only reason you'd do so is if you need mutability.
                – ShadowRanger
                Jul 1 '16 at 1:52




                Alternate solution (faster for large inputs too) when the values are known to be ASCII/latin-1 is to do bulk conversions at the C layer: bytes(sequence_of_ints_in_range_0_to_256).decode('latin-1') which makes a str faster by avoiding Python function calls for each element in favor of a bulk conversion of all elements using only C level function calls. You can wrap the above in list if you really need a list of the individual characters, but since str is already an iterable of its own characters, the only reason you'd do so is if you need mutability.
                – ShadowRanger
                Jul 1 '16 at 1:52












                up vote
                82
                down vote













                Why aren't you doing this:



                [chr(x) for x in [66,53,0,94]]


                It's called a list comprehension. You can find plenty of information on Google, but here's the link to the Python (2.6) documentation on list comprehensions. You might be more interested in the Python 3 documenation, though.






                share|improve this answer


















                • 8




                  Yes to list comprehensions.
                  – hughdbrown
                  Aug 20 '09 at 0:29






                • 4




                  Hmmmm. Maybe there needs to be a general posting on list comprehensions, generators, map(), zip(), and a lot of other speedy iteration goodness in python.
                  – hughdbrown
                  Aug 20 '09 at 0:55






                • 33




                  I guess because it's more verbose, you have to write an extra variable (twice)... If the operation is more complex and you end up writing a lambda, or you need also to drop some elements, I think a comprehension is definitively better than a map+filter, but if you already have the function you want to apply, map is more succinct.
                  – fortran
                  Jun 25 '10 at 9:43






                • 1




                  +1: Easier to read & allows you to use functions with many parameters
                  – Le Droid
                  Mar 6 '14 at 21:55










                • map(chr, [66,53,0,94]) is definitely more concise than [chr(x) for x in [66,53,0,94]].
                  – Giorgio
                  Oct 26 at 20:01














                up vote
                82
                down vote













                Why aren't you doing this:



                [chr(x) for x in [66,53,0,94]]


                It's called a list comprehension. You can find plenty of information on Google, but here's the link to the Python (2.6) documentation on list comprehensions. You might be more interested in the Python 3 documenation, though.






                share|improve this answer


















                • 8




                  Yes to list comprehensions.
                  – hughdbrown
                  Aug 20 '09 at 0:29






                • 4




                  Hmmmm. Maybe there needs to be a general posting on list comprehensions, generators, map(), zip(), and a lot of other speedy iteration goodness in python.
                  – hughdbrown
                  Aug 20 '09 at 0:55






                • 33




                  I guess because it's more verbose, you have to write an extra variable (twice)... If the operation is more complex and you end up writing a lambda, or you need also to drop some elements, I think a comprehension is definitively better than a map+filter, but if you already have the function you want to apply, map is more succinct.
                  – fortran
                  Jun 25 '10 at 9:43






                • 1




                  +1: Easier to read & allows you to use functions with many parameters
                  – Le Droid
                  Mar 6 '14 at 21:55










                • map(chr, [66,53,0,94]) is definitely more concise than [chr(x) for x in [66,53,0,94]].
                  – Giorgio
                  Oct 26 at 20:01












                up vote
                82
                down vote










                up vote
                82
                down vote









                Why aren't you doing this:



                [chr(x) for x in [66,53,0,94]]


                It's called a list comprehension. You can find plenty of information on Google, but here's the link to the Python (2.6) documentation on list comprehensions. You might be more interested in the Python 3 documenation, though.






                share|improve this answer














                Why aren't you doing this:



                [chr(x) for x in [66,53,0,94]]


                It's called a list comprehension. You can find plenty of information on Google, but here's the link to the Python (2.6) documentation on list comprehensions. You might be more interested in the Python 3 documenation, though.







                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Aug 20 '09 at 0:36

























                answered Aug 20 '09 at 0:28









                Mark Rushakoff

                179k29359370




                179k29359370







                • 8




                  Yes to list comprehensions.
                  – hughdbrown
                  Aug 20 '09 at 0:29






                • 4




                  Hmmmm. Maybe there needs to be a general posting on list comprehensions, generators, map(), zip(), and a lot of other speedy iteration goodness in python.
                  – hughdbrown
                  Aug 20 '09 at 0:55






                • 33




                  I guess because it's more verbose, you have to write an extra variable (twice)... If the operation is more complex and you end up writing a lambda, or you need also to drop some elements, I think a comprehension is definitively better than a map+filter, but if you already have the function you want to apply, map is more succinct.
                  – fortran
                  Jun 25 '10 at 9:43






                • 1




                  +1: Easier to read & allows you to use functions with many parameters
                  – Le Droid
                  Mar 6 '14 at 21:55










                • map(chr, [66,53,0,94]) is definitely more concise than [chr(x) for x in [66,53,0,94]].
                  – Giorgio
                  Oct 26 at 20:01












                • 8




                  Yes to list comprehensions.
                  – hughdbrown
                  Aug 20 '09 at 0:29






                • 4




                  Hmmmm. Maybe there needs to be a general posting on list comprehensions, generators, map(), zip(), and a lot of other speedy iteration goodness in python.
                  – hughdbrown
                  Aug 20 '09 at 0:55






                • 33




                  I guess because it's more verbose, you have to write an extra variable (twice)... If the operation is more complex and you end up writing a lambda, or you need also to drop some elements, I think a comprehension is definitively better than a map+filter, but if you already have the function you want to apply, map is more succinct.
                  – fortran
                  Jun 25 '10 at 9:43






                • 1




                  +1: Easier to read & allows you to use functions with many parameters
                  – Le Droid
                  Mar 6 '14 at 21:55










                • map(chr, [66,53,0,94]) is definitely more concise than [chr(x) for x in [66,53,0,94]].
                  – Giorgio
                  Oct 26 at 20:01







                8




                8




                Yes to list comprehensions.
                – hughdbrown
                Aug 20 '09 at 0:29




                Yes to list comprehensions.
                – hughdbrown
                Aug 20 '09 at 0:29




                4




                4




                Hmmmm. Maybe there needs to be a general posting on list comprehensions, generators, map(), zip(), and a lot of other speedy iteration goodness in python.
                – hughdbrown
                Aug 20 '09 at 0:55




                Hmmmm. Maybe there needs to be a general posting on list comprehensions, generators, map(), zip(), and a lot of other speedy iteration goodness in python.
                – hughdbrown
                Aug 20 '09 at 0:55




                33




                33




                I guess because it's more verbose, you have to write an extra variable (twice)... If the operation is more complex and you end up writing a lambda, or you need also to drop some elements, I think a comprehension is definitively better than a map+filter, but if you already have the function you want to apply, map is more succinct.
                – fortran
                Jun 25 '10 at 9:43




                I guess because it's more verbose, you have to write an extra variable (twice)... If the operation is more complex and you end up writing a lambda, or you need also to drop some elements, I think a comprehension is definitively better than a map+filter, but if you already have the function you want to apply, map is more succinct.
                – fortran
                Jun 25 '10 at 9:43




                1




                1




                +1: Easier to read & allows you to use functions with many parameters
                – Le Droid
                Mar 6 '14 at 21:55




                +1: Easier to read & allows you to use functions with many parameters
                – Le Droid
                Mar 6 '14 at 21:55












                map(chr, [66,53,0,94]) is definitely more concise than [chr(x) for x in [66,53,0,94]].
                – Giorgio
                Oct 26 at 20:01




                map(chr, [66,53,0,94]) is definitely more concise than [chr(x) for x in [66,53,0,94]].
                – Giorgio
                Oct 26 at 20:01










                up vote
                63
                down vote













                New and neat in Python 3.5:



                [*map(chr, [66, 53, 0, 94])]


                Thanks to Additional Unpacking Generalizations



                UPDATE



                Always seeking for shorter ways, I discovered this one also works:



                *map(chr, [66, 53, 0, 94]),


                Unpacking works in tuples too. Note the comma at the end. This makes it a tuple of 1 element. That is, it's equivalent to (*map(chr, [66, 53, 0, 94]),)



                It's shorter by only one char from the version with the list-brackets, but, in my opinion, better to write, because you start right ahead with the asterisk - the expansion syntax, so I feel it's softer on the mind. :)






                share|improve this answer


















                • 10




                  What's wrong with list()?
                  – Quelklef
                  Aug 12 '17 at 12:56






                • 8




                  @Quelklef list() doesn't look as neat
                  – Arijoon
                  Sep 28 '17 at 13:15






                • 3




                  @Quelklef: Also, the unpacking approach is trivially faster thanks to not needing to look up the list constructor and invoke general function call machinery. For a long input, it won't matter; for a short one, it can make a big difference. Using the above code with the input as a tuple so it's not repeatedly reconstructed, ipython microbenchmarks show the list() wrapping approach takes about 20% longer than unpacking. Mind you, in absolute terms, we're talking about 150 ns, which is trivial, but you get the idea.
                  – ShadowRanger
                  Nov 8 '17 at 4:41










                • What was wrong with the old map? Maybe with a new name (lmap?) if the new default is to return an iterator?
                  – Giorgio
                  Oct 26 at 20:04














                up vote
                63
                down vote













                New and neat in Python 3.5:



                [*map(chr, [66, 53, 0, 94])]


                Thanks to Additional Unpacking Generalizations



                UPDATE



                Always seeking for shorter ways, I discovered this one also works:



                *map(chr, [66, 53, 0, 94]),


                Unpacking works in tuples too. Note the comma at the end. This makes it a tuple of 1 element. That is, it's equivalent to (*map(chr, [66, 53, 0, 94]),)



                It's shorter by only one char from the version with the list-brackets, but, in my opinion, better to write, because you start right ahead with the asterisk - the expansion syntax, so I feel it's softer on the mind. :)






                share|improve this answer


















                • 10




                  What's wrong with list()?
                  – Quelklef
                  Aug 12 '17 at 12:56






                • 8




                  @Quelklef list() doesn't look as neat
                  – Arijoon
                  Sep 28 '17 at 13:15






                • 3




                  @Quelklef: Also, the unpacking approach is trivially faster thanks to not needing to look up the list constructor and invoke general function call machinery. For a long input, it won't matter; for a short one, it can make a big difference. Using the above code with the input as a tuple so it's not repeatedly reconstructed, ipython microbenchmarks show the list() wrapping approach takes about 20% longer than unpacking. Mind you, in absolute terms, we're talking about 150 ns, which is trivial, but you get the idea.
                  – ShadowRanger
                  Nov 8 '17 at 4:41










                • What was wrong with the old map? Maybe with a new name (lmap?) if the new default is to return an iterator?
                  – Giorgio
                  Oct 26 at 20:04












                up vote
                63
                down vote










                up vote
                63
                down vote









                New and neat in Python 3.5:



                [*map(chr, [66, 53, 0, 94])]


                Thanks to Additional Unpacking Generalizations



                UPDATE



                Always seeking for shorter ways, I discovered this one also works:



                *map(chr, [66, 53, 0, 94]),


                Unpacking works in tuples too. Note the comma at the end. This makes it a tuple of 1 element. That is, it's equivalent to (*map(chr, [66, 53, 0, 94]),)



                It's shorter by only one char from the version with the list-brackets, but, in my opinion, better to write, because you start right ahead with the asterisk - the expansion syntax, so I feel it's softer on the mind. :)






                share|improve this answer














                New and neat in Python 3.5:



                [*map(chr, [66, 53, 0, 94])]


                Thanks to Additional Unpacking Generalizations



                UPDATE



                Always seeking for shorter ways, I discovered this one also works:



                *map(chr, [66, 53, 0, 94]),


                Unpacking works in tuples too. Note the comma at the end. This makes it a tuple of 1 element. That is, it's equivalent to (*map(chr, [66, 53, 0, 94]),)



                It's shorter by only one char from the version with the list-brackets, but, in my opinion, better to write, because you start right ahead with the asterisk - the expansion syntax, so I feel it's softer on the mind. :)







                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Oct 28 at 11:25

























                answered Aug 1 '16 at 15:18









                Israel Unterman

                8,49211829




                8,49211829







                • 10




                  What's wrong with list()?
                  – Quelklef
                  Aug 12 '17 at 12:56






                • 8




                  @Quelklef list() doesn't look as neat
                  – Arijoon
                  Sep 28 '17 at 13:15






                • 3




                  @Quelklef: Also, the unpacking approach is trivially faster thanks to not needing to look up the list constructor and invoke general function call machinery. For a long input, it won't matter; for a short one, it can make a big difference. Using the above code with the input as a tuple so it's not repeatedly reconstructed, ipython microbenchmarks show the list() wrapping approach takes about 20% longer than unpacking. Mind you, in absolute terms, we're talking about 150 ns, which is trivial, but you get the idea.
                  – ShadowRanger
                  Nov 8 '17 at 4:41










                • What was wrong with the old map? Maybe with a new name (lmap?) if the new default is to return an iterator?
                  – Giorgio
                  Oct 26 at 20:04












                • 10




                  What's wrong with list()?
                  – Quelklef
                  Aug 12 '17 at 12:56






                • 8




                  @Quelklef list() doesn't look as neat
                  – Arijoon
                  Sep 28 '17 at 13:15






                • 3




                  @Quelklef: Also, the unpacking approach is trivially faster thanks to not needing to look up the list constructor and invoke general function call machinery. For a long input, it won't matter; for a short one, it can make a big difference. Using the above code with the input as a tuple so it's not repeatedly reconstructed, ipython microbenchmarks show the list() wrapping approach takes about 20% longer than unpacking. Mind you, in absolute terms, we're talking about 150 ns, which is trivial, but you get the idea.
                  – ShadowRanger
                  Nov 8 '17 at 4:41










                • What was wrong with the old map? Maybe with a new name (lmap?) if the new default is to return an iterator?
                  – Giorgio
                  Oct 26 at 20:04







                10




                10




                What's wrong with list()?
                – Quelklef
                Aug 12 '17 at 12:56




                What's wrong with list()?
                – Quelklef
                Aug 12 '17 at 12:56




                8




                8




                @Quelklef list() doesn't look as neat
                – Arijoon
                Sep 28 '17 at 13:15




                @Quelklef list() doesn't look as neat
                – Arijoon
                Sep 28 '17 at 13:15




                3




                3




                @Quelklef: Also, the unpacking approach is trivially faster thanks to not needing to look up the list constructor and invoke general function call machinery. For a long input, it won't matter; for a short one, it can make a big difference. Using the above code with the input as a tuple so it's not repeatedly reconstructed, ipython microbenchmarks show the list() wrapping approach takes about 20% longer than unpacking. Mind you, in absolute terms, we're talking about 150 ns, which is trivial, but you get the idea.
                – ShadowRanger
                Nov 8 '17 at 4:41




                @Quelklef: Also, the unpacking approach is trivially faster thanks to not needing to look up the list constructor and invoke general function call machinery. For a long input, it won't matter; for a short one, it can make a big difference. Using the above code with the input as a tuple so it's not repeatedly reconstructed, ipython microbenchmarks show the list() wrapping approach takes about 20% longer than unpacking. Mind you, in absolute terms, we're talking about 150 ns, which is trivial, but you get the idea.
                – ShadowRanger
                Nov 8 '17 at 4:41












                What was wrong with the old map? Maybe with a new name (lmap?) if the new default is to return an iterator?
                – Giorgio
                Oct 26 at 20:04




                What was wrong with the old map? Maybe with a new name (lmap?) if the new default is to return an iterator?
                – Giorgio
                Oct 26 at 20:04










                up vote
                20
                down vote













                List-returning map function has the advantage of saving typing, especially during interactive sessions. You can define lmap function (on the analogy of python2's imap) that returns list:



                lmap = lambda func, *iterable: list(map(func, *iterable))


                Then calling lmap instead of map will do the job:
                lmap(str, x) is shorter by 5 characters (30% in this case) than list(map(str, x)) and is certainly shorter than [str(v) for v in x]. You may create similar functions for filter too.



                There was a comment to the original question:




                I would suggest a rename to Getting map() to return a list in Python 3.* as it applies to all Python3 versions. Is there a way to do this? – meawoppl Jan 24 at 17:58




                It is possible to do that, but it is a very bad idea. Just for fun, here's how you may (but should not) do it:



                __global_map = map #keep reference to the original map
                lmap = lambda func, *iterable: list(__global_map(func, *iterable)) # using "map" here will cause infinite recursion
                map = lmap
                x = [1, 2, 3]
                map(str, x) #test
                map = __global_map #restore the original map and don't do that again
                map(str, x) #iterator





                share|improve this answer


























                  up vote
                  20
                  down vote













                  List-returning map function has the advantage of saving typing, especially during interactive sessions. You can define lmap function (on the analogy of python2's imap) that returns list:



                  lmap = lambda func, *iterable: list(map(func, *iterable))


                  Then calling lmap instead of map will do the job:
                  lmap(str, x) is shorter by 5 characters (30% in this case) than list(map(str, x)) and is certainly shorter than [str(v) for v in x]. You may create similar functions for filter too.



                  There was a comment to the original question:




                  I would suggest a rename to Getting map() to return a list in Python 3.* as it applies to all Python3 versions. Is there a way to do this? – meawoppl Jan 24 at 17:58




                  It is possible to do that, but it is a very bad idea. Just for fun, here's how you may (but should not) do it:



                  __global_map = map #keep reference to the original map
                  lmap = lambda func, *iterable: list(__global_map(func, *iterable)) # using "map" here will cause infinite recursion
                  map = lmap
                  x = [1, 2, 3]
                  map(str, x) #test
                  map = __global_map #restore the original map and don't do that again
                  map(str, x) #iterator





                  share|improve this answer
























                    up vote
                    20
                    down vote










                    up vote
                    20
                    down vote









                    List-returning map function has the advantage of saving typing, especially during interactive sessions. You can define lmap function (on the analogy of python2's imap) that returns list:



                    lmap = lambda func, *iterable: list(map(func, *iterable))


                    Then calling lmap instead of map will do the job:
                    lmap(str, x) is shorter by 5 characters (30% in this case) than list(map(str, x)) and is certainly shorter than [str(v) for v in x]. You may create similar functions for filter too.



                    There was a comment to the original question:




                    I would suggest a rename to Getting map() to return a list in Python 3.* as it applies to all Python3 versions. Is there a way to do this? – meawoppl Jan 24 at 17:58




                    It is possible to do that, but it is a very bad idea. Just for fun, here's how you may (but should not) do it:



                    __global_map = map #keep reference to the original map
                    lmap = lambda func, *iterable: list(__global_map(func, *iterable)) # using "map" here will cause infinite recursion
                    map = lmap
                    x = [1, 2, 3]
                    map(str, x) #test
                    map = __global_map #restore the original map and don't do that again
                    map(str, x) #iterator





                    share|improve this answer














                    List-returning map function has the advantage of saving typing, especially during interactive sessions. You can define lmap function (on the analogy of python2's imap) that returns list:



                    lmap = lambda func, *iterable: list(map(func, *iterable))


                    Then calling lmap instead of map will do the job:
                    lmap(str, x) is shorter by 5 characters (30% in this case) than list(map(str, x)) and is certainly shorter than [str(v) for v in x]. You may create similar functions for filter too.



                    There was a comment to the original question:




                    I would suggest a rename to Getting map() to return a list in Python 3.* as it applies to all Python3 versions. Is there a way to do this? – meawoppl Jan 24 at 17:58




                    It is possible to do that, but it is a very bad idea. Just for fun, here's how you may (but should not) do it:



                    __global_map = map #keep reference to the original map
                    lmap = lambda func, *iterable: list(__global_map(func, *iterable)) # using "map" here will cause infinite recursion
                    map = lmap
                    x = [1, 2, 3]
                    map(str, x) #test
                    map = __global_map #restore the original map and don't do that again
                    map(str, x) #iterator






                    share|improve this answer














                    share|improve this answer



                    share|improve this answer








                    edited May 25 at 18:01









                    Michael Goldshteyn

                    49.7k1499160




                    49.7k1499160










                    answered Jul 1 '14 at 9:41









                    Boris Gorelik

                    11.3k2296143




                    11.3k2296143




















                        up vote
                        11
                        down vote













                        I'm not familiar with Python 3.1, but will this work?



                        [chr(x) for x in [66, 53, 0, 94]]





                        share|improve this answer
















                        • 1




                          works perfectly.
                          – ExceptionSlayer
                          Apr 18 '16 at 9:52














                        up vote
                        11
                        down vote













                        I'm not familiar with Python 3.1, but will this work?



                        [chr(x) for x in [66, 53, 0, 94]]





                        share|improve this answer
















                        • 1




                          works perfectly.
                          – ExceptionSlayer
                          Apr 18 '16 at 9:52












                        up vote
                        11
                        down vote










                        up vote
                        11
                        down vote









                        I'm not familiar with Python 3.1, but will this work?



                        [chr(x) for x in [66, 53, 0, 94]]





                        share|improve this answer












                        I'm not familiar with Python 3.1, but will this work?



                        [chr(x) for x in [66, 53, 0, 94]]






                        share|improve this answer












                        share|improve this answer



                        share|improve this answer










                        answered Aug 20 '09 at 0:28









                        Andrew Keeton

                        14.2k53464




                        14.2k53464







                        • 1




                          works perfectly.
                          – ExceptionSlayer
                          Apr 18 '16 at 9:52












                        • 1




                          works perfectly.
                          – ExceptionSlayer
                          Apr 18 '16 at 9:52







                        1




                        1




                        works perfectly.
                        – ExceptionSlayer
                        Apr 18 '16 at 9:52




                        works perfectly.
                        – ExceptionSlayer
                        Apr 18 '16 at 9:52










                        up vote
                        3
                        down vote













                        Converting my old comment for better visibility: For a "better way to do this" without map entirely, if your inputs are known to be ASCII ordinals, it's generally much faster to convert to bytes and decode, a la bytes(list_of_ordinals).decode('ascii'). That gets you a str of the values, but if you need a list for mutability or the like, you can just convert it (and it's still faster). For example, in ipython microbenchmarks converting 45 inputs:



                        >>> %%timeit -r5 ordinals = list(range(45))
                        ... list(map(chr, ordinals))
                        ...
                        3.91 µs ± 60.2 ns per loop (mean ± std. dev. of 5 runs, 100000 loops each)

                        >>> %%timeit -r5 ordinals = list(range(45))
                        ... [*map(chr, ordinals)]
                        ...
                        3.84 µs ± 219 ns per loop (mean ± std. dev. of 5 runs, 100000 loops each)

                        >>> %%timeit -r5 ordinals = list(range(45))
                        ... [*bytes(ordinals).decode('ascii')]
                        ...
                        1.43 µs ± 49.7 ns per loop (mean ± std. dev. of 5 runs, 1000000 loops each)

                        >>> %%timeit -r5 ordinals = list(range(45))
                        ... bytes(ordinals).decode('ascii')
                        ...
                        781 ns ± 15.9 ns per loop (mean ± std. dev. of 5 runs, 1000000 loops each)


                        If you leave it as a str, it takes ~20% of the time of the fastest map solutions; even converting back to list it's still less than 40% of the fastest map solution. Bulk convert via bytes and bytes.decode then bulk converting back to list saves a lot of work, but as noted, only works if all your inputs are ASCII ordinals (or ordinals in some one byte per character locale specific encoding, e.g. latin-1).






                        share|improve this answer
























                          up vote
                          3
                          down vote













                          Converting my old comment for better visibility: For a "better way to do this" without map entirely, if your inputs are known to be ASCII ordinals, it's generally much faster to convert to bytes and decode, a la bytes(list_of_ordinals).decode('ascii'). That gets you a str of the values, but if you need a list for mutability or the like, you can just convert it (and it's still faster). For example, in ipython microbenchmarks converting 45 inputs:



                          >>> %%timeit -r5 ordinals = list(range(45))
                          ... list(map(chr, ordinals))
                          ...
                          3.91 µs ± 60.2 ns per loop (mean ± std. dev. of 5 runs, 100000 loops each)

                          >>> %%timeit -r5 ordinals = list(range(45))
                          ... [*map(chr, ordinals)]
                          ...
                          3.84 µs ± 219 ns per loop (mean ± std. dev. of 5 runs, 100000 loops each)

                          >>> %%timeit -r5 ordinals = list(range(45))
                          ... [*bytes(ordinals).decode('ascii')]
                          ...
                          1.43 µs ± 49.7 ns per loop (mean ± std. dev. of 5 runs, 1000000 loops each)

                          >>> %%timeit -r5 ordinals = list(range(45))
                          ... bytes(ordinals).decode('ascii')
                          ...
                          781 ns ± 15.9 ns per loop (mean ± std. dev. of 5 runs, 1000000 loops each)


                          If you leave it as a str, it takes ~20% of the time of the fastest map solutions; even converting back to list it's still less than 40% of the fastest map solution. Bulk convert via bytes and bytes.decode then bulk converting back to list saves a lot of work, but as noted, only works if all your inputs are ASCII ordinals (or ordinals in some one byte per character locale specific encoding, e.g. latin-1).






                          share|improve this answer






















                            up vote
                            3
                            down vote










                            up vote
                            3
                            down vote









                            Converting my old comment for better visibility: For a "better way to do this" without map entirely, if your inputs are known to be ASCII ordinals, it's generally much faster to convert to bytes and decode, a la bytes(list_of_ordinals).decode('ascii'). That gets you a str of the values, but if you need a list for mutability or the like, you can just convert it (and it's still faster). For example, in ipython microbenchmarks converting 45 inputs:



                            >>> %%timeit -r5 ordinals = list(range(45))
                            ... list(map(chr, ordinals))
                            ...
                            3.91 µs ± 60.2 ns per loop (mean ± std. dev. of 5 runs, 100000 loops each)

                            >>> %%timeit -r5 ordinals = list(range(45))
                            ... [*map(chr, ordinals)]
                            ...
                            3.84 µs ± 219 ns per loop (mean ± std. dev. of 5 runs, 100000 loops each)

                            >>> %%timeit -r5 ordinals = list(range(45))
                            ... [*bytes(ordinals).decode('ascii')]
                            ...
                            1.43 µs ± 49.7 ns per loop (mean ± std. dev. of 5 runs, 1000000 loops each)

                            >>> %%timeit -r5 ordinals = list(range(45))
                            ... bytes(ordinals).decode('ascii')
                            ...
                            781 ns ± 15.9 ns per loop (mean ± std. dev. of 5 runs, 1000000 loops each)


                            If you leave it as a str, it takes ~20% of the time of the fastest map solutions; even converting back to list it's still less than 40% of the fastest map solution. Bulk convert via bytes and bytes.decode then bulk converting back to list saves a lot of work, but as noted, only works if all your inputs are ASCII ordinals (or ordinals in some one byte per character locale specific encoding, e.g. latin-1).






                            share|improve this answer












                            Converting my old comment for better visibility: For a "better way to do this" without map entirely, if your inputs are known to be ASCII ordinals, it's generally much faster to convert to bytes and decode, a la bytes(list_of_ordinals).decode('ascii'). That gets you a str of the values, but if you need a list for mutability or the like, you can just convert it (and it's still faster). For example, in ipython microbenchmarks converting 45 inputs:



                            >>> %%timeit -r5 ordinals = list(range(45))
                            ... list(map(chr, ordinals))
                            ...
                            3.91 µs ± 60.2 ns per loop (mean ± std. dev. of 5 runs, 100000 loops each)

                            >>> %%timeit -r5 ordinals = list(range(45))
                            ... [*map(chr, ordinals)]
                            ...
                            3.84 µs ± 219 ns per loop (mean ± std. dev. of 5 runs, 100000 loops each)

                            >>> %%timeit -r5 ordinals = list(range(45))
                            ... [*bytes(ordinals).decode('ascii')]
                            ...
                            1.43 µs ± 49.7 ns per loop (mean ± std. dev. of 5 runs, 1000000 loops each)

                            >>> %%timeit -r5 ordinals = list(range(45))
                            ... bytes(ordinals).decode('ascii')
                            ...
                            781 ns ± 15.9 ns per loop (mean ± std. dev. of 5 runs, 1000000 loops each)


                            If you leave it as a str, it takes ~20% of the time of the fastest map solutions; even converting back to list it's still less than 40% of the fastest map solution. Bulk convert via bytes and bytes.decode then bulk converting back to list saves a lot of work, but as noted, only works if all your inputs are ASCII ordinals (or ordinals in some one byte per character locale specific encoding, e.g. latin-1).







                            share|improve this answer












                            share|improve this answer



                            share|improve this answer










                            answered Nov 8 '17 at 4:52









                            ShadowRanger

                            56.2k44992




                            56.2k44992




















                                up vote
                                0
                                down vote













                                list(map(chr, [66, 53, 0, 94]))



                                map(func, *iterables) --> map object
                                Make an iterator that computes the function using arguments from
                                each of the iterables. Stops when the shortest iterable is exhausted.



                                "Make an iterator"




                                means it will return an iterator.




                                "that computes the function using arguments from each of the iterables"




                                means that the next() function of the iterator will take one value of each iterables and pass each of them to one positional parameter of the function.



                                So you get an iterator from the map() funtion and jsut pass it to the list() builtin function or use list comprehensions.






                                share|improve this answer
























                                  up vote
                                  0
                                  down vote













                                  list(map(chr, [66, 53, 0, 94]))



                                  map(func, *iterables) --> map object
                                  Make an iterator that computes the function using arguments from
                                  each of the iterables. Stops when the shortest iterable is exhausted.



                                  "Make an iterator"




                                  means it will return an iterator.




                                  "that computes the function using arguments from each of the iterables"




                                  means that the next() function of the iterator will take one value of each iterables and pass each of them to one positional parameter of the function.



                                  So you get an iterator from the map() funtion and jsut pass it to the list() builtin function or use list comprehensions.






                                  share|improve this answer






















                                    up vote
                                    0
                                    down vote










                                    up vote
                                    0
                                    down vote









                                    list(map(chr, [66, 53, 0, 94]))



                                    map(func, *iterables) --> map object
                                    Make an iterator that computes the function using arguments from
                                    each of the iterables. Stops when the shortest iterable is exhausted.



                                    "Make an iterator"




                                    means it will return an iterator.




                                    "that computes the function using arguments from each of the iterables"




                                    means that the next() function of the iterator will take one value of each iterables and pass each of them to one positional parameter of the function.



                                    So you get an iterator from the map() funtion and jsut pass it to the list() builtin function or use list comprehensions.






                                    share|improve this answer












                                    list(map(chr, [66, 53, 0, 94]))



                                    map(func, *iterables) --> map object
                                    Make an iterator that computes the function using arguments from
                                    each of the iterables. Stops when the shortest iterable is exhausted.



                                    "Make an iterator"




                                    means it will return an iterator.




                                    "that computes the function using arguments from each of the iterables"




                                    means that the next() function of the iterator will take one value of each iterables and pass each of them to one positional parameter of the function.



                                    So you get an iterator from the map() funtion and jsut pass it to the list() builtin function or use list comprehensions.







                                    share|improve this answer












                                    share|improve this answer



                                    share|improve this answer










                                    answered Nov 7 '17 at 9:04









                                    Ini

                                    216315




                                    216315




















                                        up vote
                                        0
                                        down vote













                                        In addition to above answers in Python 3, we may simply create a list of result values from a map as



                                        li = 
                                        for x in map(chr,[66,53,0,94]):
                                        li.append(x)

                                        print (li)
                                        >>>['B', '5', 'x00', '^']


                                        We may generalize by another example where I was struck, operations on map can also be handled in similar fashion like in regex problem, we can write function to obtain list of items to map and get result set at the same time. Ex.



                                        b = 'Strings: 1,072, Another String: 474 '
                                        li =
                                        for x in map(int,map(int, re.findall('d+', b))):
                                        li.append(x)

                                        print (li)
                                        >>>[1, 72, 474]





                                        share|improve this answer




















                                        • @miradulo I supposed in Python 2, a list was returned, but in Python 3, only type is returned and I just tried to give in same format. If you think its needless, there maybe people like me who can find it useful and thats why I added.
                                          – Harry_pb
                                          Jun 15 at 17:32






                                        • 1




                                          When there is already a list comprehension, a list function, and an unpacking answer, an explicit for loop doesn’t add much IMHO.
                                          – miradulo
                                          Jun 15 at 20:04














                                        up vote
                                        0
                                        down vote













                                        In addition to above answers in Python 3, we may simply create a list of result values from a map as



                                        li = 
                                        for x in map(chr,[66,53,0,94]):
                                        li.append(x)

                                        print (li)
                                        >>>['B', '5', 'x00', '^']


                                        We may generalize by another example where I was struck, operations on map can also be handled in similar fashion like in regex problem, we can write function to obtain list of items to map and get result set at the same time. Ex.



                                        b = 'Strings: 1,072, Another String: 474 '
                                        li =
                                        for x in map(int,map(int, re.findall('d+', b))):
                                        li.append(x)

                                        print (li)
                                        >>>[1, 72, 474]





                                        share|improve this answer




















                                        • @miradulo I supposed in Python 2, a list was returned, but in Python 3, only type is returned and I just tried to give in same format. If you think its needless, there maybe people like me who can find it useful and thats why I added.
                                          – Harry_pb
                                          Jun 15 at 17:32






                                        • 1




                                          When there is already a list comprehension, a list function, and an unpacking answer, an explicit for loop doesn’t add much IMHO.
                                          – miradulo
                                          Jun 15 at 20:04












                                        up vote
                                        0
                                        down vote










                                        up vote
                                        0
                                        down vote









                                        In addition to above answers in Python 3, we may simply create a list of result values from a map as



                                        li = 
                                        for x in map(chr,[66,53,0,94]):
                                        li.append(x)

                                        print (li)
                                        >>>['B', '5', 'x00', '^']


                                        We may generalize by another example where I was struck, operations on map can also be handled in similar fashion like in regex problem, we can write function to obtain list of items to map and get result set at the same time. Ex.



                                        b = 'Strings: 1,072, Another String: 474 '
                                        li =
                                        for x in map(int,map(int, re.findall('d+', b))):
                                        li.append(x)

                                        print (li)
                                        >>>[1, 72, 474]





                                        share|improve this answer












                                        In addition to above answers in Python 3, we may simply create a list of result values from a map as



                                        li = 
                                        for x in map(chr,[66,53,0,94]):
                                        li.append(x)

                                        print (li)
                                        >>>['B', '5', 'x00', '^']


                                        We may generalize by another example where I was struck, operations on map can also be handled in similar fashion like in regex problem, we can write function to obtain list of items to map and get result set at the same time. Ex.



                                        b = 'Strings: 1,072, Another String: 474 '
                                        li =
                                        for x in map(int,map(int, re.findall('d+', b))):
                                        li.append(x)

                                        print (li)
                                        >>>[1, 72, 474]






                                        share|improve this answer












                                        share|improve this answer



                                        share|improve this answer










                                        answered Jun 15 at 16:35









                                        Harry_pb

                                        1,61511125




                                        1,61511125











                                        • @miradulo I supposed in Python 2, a list was returned, but in Python 3, only type is returned and I just tried to give in same format. If you think its needless, there maybe people like me who can find it useful and thats why I added.
                                          – Harry_pb
                                          Jun 15 at 17:32






                                        • 1




                                          When there is already a list comprehension, a list function, and an unpacking answer, an explicit for loop doesn’t add much IMHO.
                                          – miradulo
                                          Jun 15 at 20:04
















                                        • @miradulo I supposed in Python 2, a list was returned, but in Python 3, only type is returned and I just tried to give in same format. If you think its needless, there maybe people like me who can find it useful and thats why I added.
                                          – Harry_pb
                                          Jun 15 at 17:32






                                        • 1




                                          When there is already a list comprehension, a list function, and an unpacking answer, an explicit for loop doesn’t add much IMHO.
                                          – miradulo
                                          Jun 15 at 20:04















                                        @miradulo I supposed in Python 2, a list was returned, but in Python 3, only type is returned and I just tried to give in same format. If you think its needless, there maybe people like me who can find it useful and thats why I added.
                                        – Harry_pb
                                        Jun 15 at 17:32




                                        @miradulo I supposed in Python 2, a list was returned, but in Python 3, only type is returned and I just tried to give in same format. If you think its needless, there maybe people like me who can find it useful and thats why I added.
                                        – Harry_pb
                                        Jun 15 at 17:32




                                        1




                                        1




                                        When there is already a list comprehension, a list function, and an unpacking answer, an explicit for loop doesn’t add much IMHO.
                                        – miradulo
                                        Jun 15 at 20:04




                                        When there is already a list comprehension, a list function, and an unpacking answer, an explicit for loop doesn’t add much IMHO.
                                        – miradulo
                                        Jun 15 at 20:04










                                        up vote
                                        0
                                        down vote













                                        Using list comprehension in python and basic map function utility, one can do this also:



                                        chi = [x for x in map(chr,[66,53,0,94])]






                                        share|improve this answer






















                                        • chi list will be containing, the ASIC value of the given elements.
                                          – darshan k s
                                          Nov 11 at 17:01














                                        up vote
                                        0
                                        down vote













                                        Using list comprehension in python and basic map function utility, one can do this also:



                                        chi = [x for x in map(chr,[66,53,0,94])]






                                        share|improve this answer






















                                        • chi list will be containing, the ASIC value of the given elements.
                                          – darshan k s
                                          Nov 11 at 17:01












                                        up vote
                                        0
                                        down vote










                                        up vote
                                        0
                                        down vote









                                        Using list comprehension in python and basic map function utility, one can do this also:



                                        chi = [x for x in map(chr,[66,53,0,94])]






                                        share|improve this answer














                                        Using list comprehension in python and basic map function utility, one can do this also:



                                        chi = [x for x in map(chr,[66,53,0,94])]







                                        share|improve this answer














                                        share|improve this answer



                                        share|improve this answer








                                        edited Nov 11 at 17:29









                                        rassar

                                        2,20811029




                                        2,20811029










                                        answered Nov 11 at 16:57









                                        darshan k s

                                        1




                                        1











                                        • chi list will be containing, the ASIC value of the given elements.
                                          – darshan k s
                                          Nov 11 at 17:01
















                                        • chi list will be containing, the ASIC value of the given elements.
                                          – darshan k s
                                          Nov 11 at 17:01















                                        chi list will be containing, the ASIC value of the given elements.
                                        – darshan k s
                                        Nov 11 at 17:01




                                        chi list will be containing, the ASIC value of the given elements.
                                        – darshan k s
                                        Nov 11 at 17:01

















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