Analyzing python iterables with all() and any()

all() and any() are built-in functions that help analyze python iterables.

all()

all() returns True if all elements of the iterable are true (or if the iterable is empty).

Python 3.7.4

>>> x = [2, 3, 5, 1]
>>> all(x)
True

>>> x = [2, 3, 5, 0]
>>> all(x)
False

>>> x = []
>>> all(x)
True

In the second instance, False is returned because of the 0 in the list. Note that this would not be the case if the 0 was a string.

>>> x = [2, 3, 5, '0']
>>> all(x)
True

For checking dictionary values,

>>> x = {'item1': 'pen', 'item2': 'paper', 'item3': 'book'}
>>> all(x.values())
True

>>> x = {'item1': 'pen', 'item2': 'paper', 'item3': False}
>>> all(x.values())
False

>>> x = {}
>>> all(x)
True

any()

any() returns True if any element of the iterable is true. If the iterable is empty, it returns False.

>>> x = [2, 3, 5, 1]
>>> any(x)
True

>>> x = [2, 3, 5, 0]
>>> any(x)
True

>>> x = [0, 0, 0, '0']
>>> any(x)
True

>>> x = [0, 0, 0, 0]
>>> any(x)
False

>>> x = []
>>> any(x)
False

It also works the same for dictionaries:

>>> x = {'item1': 'pen', 'item2': 'paper', 'item3': 'book'}
>>> any(x)
True

>>> x = {'item1': 'pen', 'item2': 'paper', 'item3': False}
>>> any(x)
True

>>> x = {}
>>> any(x)
False

Comments

[Dylan Anthony]

Nice post! Worth that they will short circuit. Meaning all will return as soon as it sees a False and any will exit as soon as it sees True.

So if you’re going to have a bunch of calculated values you should use a generator of some sort rather than building the list in advance.