filter¶
Description¶
Returns a sequence from those elements of iterable for which function returns True.
Syntax¶
filter (function, iterable)
- function
- Required. A function. If set to None returns only elements that are True.
- iterable
- Required. Any iterable sequence.
Return Value¶
same as returned by function
Time Complexity¶
#TODO
Note¶
Note that filter(function, iterable) is equivalent to [item for item in iterable if function(item)] if function is not None and [item for item in iterable if item] if function is None.
See itertools.ifilter() and itertools.ifilterfalse() for iterator versions of this function, including a variation that filters for elements where the function returns False.
Example 1¶
>>> def f(x):
... if x > 0:
... return x
>>> filter(f, [-1, 0, 1])
[1]
Example 2¶
>>> filter(None, (0, 1, True))
(1, True)
See Also¶
map(), reduce() and Comprehensions and Generator Expression.