all() function in Python

all() function in Python

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Introduction

The all() function returns True if all elements in the given iterable are true. If not, it returns False.

The all() function takes a single parameter iterable and returns True if all elements in an iterable are true or False if any element in an iterable is false.

The syntax of the all() function is:

all(iterable)

where iterable can be any iterable (list, tuple, dictionary, etc.) which contains the elements.

Since all() can return True and False depending upon the conditions, we can summarise its return value in the following table:

ConditionReturn Value
All values are TrueTrue
All values are FalseFalse
One of the values in True (others are False)False
One of the values is False (others are True)False
Empty IterableTrue

Working of all() for lists, tuples, and sets

## All values are true
list1 = [1, 2, 3, 4, 5]
print(all(list1))

## All values are false
list2 = [0, False]
print(all(list2))

## One value is false(i.e. 0)
list3 = [1, 2, 3, 4, 0]
print(all(list3))

## One value is true(i.e. 1)
list4 = [0, False, 1]
print(all(list4))

## Empty iterable
list5 = []
print(all(list5))

Output:

True
False
False
False
True

Working of all() for strings

string1 = "I am learning Python built-ins"
print(all(string1))

## 0 is False but '0' is True
string2 = '00000'
print(all(string2))

## Empty String
string3 = ''
print(all(string3))

Output:

True
True
True

Working of all() for dictionaries

## O is False
dict1 = {0: 'False', 1: 'True'}
print(all(dict1))

## All values are true
dict2 = {1: 'True', 2: 'True'}
print(all(dict2))

## One value is False
dict3 = {1: 'True', False: 0}
print(all(dict3))

## Empty dictionary
dict4 = {}
print(all(dict4))

## 0 is False but '0' is True
dict5 = {'0': 'False'}
print(all(dict5))

Output:

False
True
False
True
True

In the case of dictionaries, if all keys (not values) are True or the dictionary is empty, all() returns True. Else, it returns False for all other cases.

Note: 0 is considered as False and 1 is considered as True in Python. In addition to that, '0' is True whereas 0 is False.

Conclusion

In this part, we learned about the Python all() function with the help of examples.

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