Python all()

Python all() function checks if every element in an iterable (like a list or tuple) is True. It returns True only if all elements are True or if the iterable is empty. It’s a quick way to verify conditions across a collection.

all() Syntax

result = all(iterable)
  • result: Stores the True/False outcome of the all() check.
  • all(): The built-in Python function performing the check.
  • iterable: The list, tuple, or other collection you want to evaluate.

Example 1: Checking if All Elements in a List Are True with Python all()

my_list = [True, 1, "hello"]
result = all(my_list)
print(result)

Code Explanation

  • Line 1: Creates a list with various True-equivalent values.
  • Line 2: Applies all() to my_list. Since all elements are truthy, result becomes True.
  • Line 3: Prints the outcome (True) to the console.

Output

True


Example 2: How Python all() Works for Lists?

my_list = [1, 2, 3, 4]
result = all(my_list)
print(result)

my_list_with_zero = [1, 2, 0, 4]
result = all(my_list_with_zero)
print(result)

empty_list = []
result = all(empty_list)
print(result)

Code Explanation

  • For lists, all() checks each element
  • An empty list is considered True
  • If any element in the list evaluates to False, then all() returns False

Output

True
False
True


Example 3: Checking if All Elements in a List Meet a Condition with Python all()

numbers = [2, 4, 6, 0]
result = all(num % 2 == 0 for num in numbers)
print(result)

Code Explanation

  • Line 1: Creates a list of numbers.
  • Line 2: Uses a generator expression within all(). It checks if each num is even. Since 0 is present (and 0 % 2 == 0 is True), result is False.
  • Line 3: Prints the outcome (False) to the console.

Output

False


Example 4: How Python all() Works for Strings?

my_string = "Hello World"
result = all(my_string)
print(result)

empty_string = ""
result = all(empty_string)
print(result)

Code Explanation

  • In the case of strings, all() considers any non-empty string as True. Even a string with just whitespace is considered True.
  • An empty string is evaluated as False.

Output

True
True


Example 5: How Python all() Works with Python Dictionaries?

my_dict = {'a': 1, 'b': 2, 'c': 3}
result = all(my_dict)
print(result)

empty_dict = {}
result = all(empty_dict)
print(result)

my_dict_with_false = {'a': 1, 'b': 0, 'c': 3}
result = all(my_dict_with_false)
print(result)

Code Explanation

  • For dictionaries, all() checks the keys, not the values
  • An empty dictionary is considered True
  • If any key in the dictionary evaluates to False, then all() returns False

Output

True
True
False


Also Read

Python abs()

Python any()