Learn Web Development with Python

filter

According to the Python documentation:

filter(function, iterable) construct an iterator from those elements of iterable for which function returns True. iterable may be either a sequence, a container which supports iteration, or an iterator. If function is None, the identity function is assumed, that is, all elements of iterable that are false are removed.

Let's see a very quick example:

# filter.py>>> test = [2, 5, 8, 0, 0, 1, 0]>>> _(filter(None, test))[2, 5, 8, 1]>>> _(filter(lambda x: x, test))  # equivalent to previous one[2, 5, 8, 1]>>> _(filter(lambda x: x > 4, test))  # keep only items > 4[5, 8]

In the preceding code, notice how the second call to filter is equivalent to the first one. If we pass a function that takes one argument ...