Python Built-in Methods – Python all() Function

Determines whether all items in an iterable are True

Usage

The `all()` function returns True if all items in an iterable are True. Otherwise, it returns False.

If the iterable is empty, the function returns True.

Syntax

all(iterable)

 Parameter Condition Description iterable Required An iterable of type (list, string, tuple, set, dictionary etc.)

Falsy Values

In Python, all the following values are considered False.

• Constants defined to be false: `None` and `False`.
• Zero of any numeric type: `0``0.0``0j``Decimal(0)``Fraction(0, 1)`
• Empty sequences and collections: `''``()``[]``{}``set()``range(0)`

Basic Examples

``````# Check if all items in a list are True

L = [1, 1, 1]
print(all(L))   # Prints True

L = [0, 1, 1]
print(all(L))   # Prints False``````

Here are some scenarios where `all()` returns False.

``````L = [True, 0, 1]
print(all(L))   # Prints False

T = ('', 'red', 'green')
print(all(T))   # Prints False

S = {0j, 3+4j}
print(all(S))   # Prints False``````

all() on a Dictionary

When you use `all()` function on a dictionary, it checks if all the keys are true, not the values.

``````D1 = {0: 'Zero', 1: 'One', 2: 'Two'}
print(all(D1))   # Prints False

D2 = {'Zero': 0, 'One': 1, 'Two': 2}
print(all(D2))   # Prints True``````

all() on Empty Iterable

If the iterable is empty, the function returns True.

``````# empty iterable
L = []
print(all(L))   # Prints True

# iterable with empty items
L = [[], []]
print(all(L))   # Prints False``````

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