Python any() Function

Python’s built-in any(x) function takes one iterable as an argument x such as a list, tuple, or dictionary. It returns True if at least one of the elements in the iterable evaluates to True using implicit Boolean conversion, otherwise it returns False. If the iterable is empty, e.g., any([]), it returns False because the condition is not satisfied for any element.

Interactive Code Shell

Consider the following interactive code snippet:

Exercise: Remove one element from the list so that the any() function returns False.

Hint: Only one element evaluates to True.

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Example any() for Lists

The following code shows you how to use the any() function on different lists.

# Boolean list with False value
print(any([True, False, True, True]))
# True


# Boolean list without False value
print(any([True, True]))
# True


# Integer list with 0 value
print(any([1, 2, -1, 0]))
# True


# Integer list without 0 value
print(any([1, 2, -1]))
# True


# Nested list with empty inner list
print(any([[], [1, 2, 3]]))
# True


# Nested list with two empty inner lists
print(any([[], []]))
# False


# Empty List
print(any([]))
# False

Example any() for Tuples

If you use the any() function on tuples, it’ll return a Boolean value that indicates whether all tuple elements evaluate to True.

print(any((1, 2, 3)))
# True

print(any((0, 0, 0)))
# False

print(any((False, 2==3, -1)))
# True

print(any((True, 3, 1!=1)))
# True

Example any() for Dicts

The any() function on dictionaries checks for the iterable of keys (not values) whether at least one key evaluates to True. If this is the case, the return value is True, otherwise it’s False.

d = {'': 10000,
     0: 5000,
     tuple(): 0}

print(any(d))
# False

d['x'] = 100000


print(any(d))
# True

Implementation

According to the official Python documentation, the any() function is semantically equivalent to the following code snippet:

def any(iterable):
    for element in iterable:
        if element:
            return True
    return False

So, it goes over all elements in the iterable and uses the element as an if condition to check whether it evaluates to True or False. As soon as one True element is detected, it aborts the loop and returns True. This is an optimization called short circuiting and it means that only the first True value is evaluated!

Python any() Function with For Loop

You can also dynamically create an iterable using a generator expression and pass it into the any() function. This may be called an “any() function with a for loop“.

print(any(x**2 == 16 for x in range(10)))
# True

You use the condition x**2 == 16 which holds only for x=4. As you apply this expression for all x values from 0 to 9 (included) by using the range() function, it mostly returns False. Due to short circuiting, the any() function returns True after evaluating the fifth element x=4.

Summary

Python’s built-in any(x) function takes one iterable as an argument x such as a list, tuple, or dictionary.

It returns True if at least one of the elements in the iterable evaluates to True using implicit Boolean conversion, otherwise it returns False. If the iterable is empty, any([]) returns False because the condition is not satisfied for any element.

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