Python 3 Map function is not Calling up function

Python 3 Map function is not Calling up function

map() returns an iterator, and will not process elements until you ask it to.

Turn it into a list to force all elements to be processed:

list(map(self.do_someting,range(10)))

or use collections.deque() with the length set to 0 to not produce a list if you dont need the map output:

from collections import deque

deque(map(self.do_someting, range(10)))

but note that simply using a for loop is far more readable for any future maintainers of your code:

for i in range(10):
    self.do_someting(i)

Before Python 3, map() returned a list, not an iterator. So your example would work in Python 2.7.

list() creates a new list by iterating over its argument. ( list() is NOT JUST a type conversion from say tuple to list. So list(list((1,2))) returns [1,2]. ) So list(map(…)) is backwards compatible with Python 2.7.

Python 3 Map function is not Calling up function

I just want to add the following:

With multiple iterables, the iterator stops when the shortest iterable is exhausted [ https://docs.python.org/3.4/library/functions.html#map ]

Python 2.7.6 (default, Mar 22 2014, 22:59:56)

>>> list(map(lambda a, b: [a, b], [1, 2, 3], [a, b]))
[[1, a], [2, b], [3, None]]

Python 3.4.0 (default, Apr 11 2014, 13:05:11)

>>> list(map(lambda a, b: [a, b], [1, 2, 3], [a, b]))
[[1, a], [2, b]]

That difference makes the answer about simple wrapping with list(...) not completely correct

The same could be achieved with:

>>> import itertools
>>> [[a, b] for a, b in itertools.zip_longest([1, 2, 3], [a, b])]
[[1, a], [2, b], [3, None]]

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