The Python library provides many useful in-built functions and all()
function is one of them. This utility method an iterable (list, tuple, dictionary etc.) as an argument and then returns True
if all the elements in iterable are true, otherwise it returns False
. If iterable passed is empty, then all()
method returns True
.
Python all() Syntax
Parameters:
all()
method include:- Lists, e.g. [45,50,True]
- Tuples, e.g. (52,64,17)
- Dictionaries, e.g. {70:"Dog", 71:"Cat"}
- Strings, e.g. "Ben", "Jacob".
Return value and equivalent code:
all()
function is an equivalent to a series of successive logical and operations on the passed iterable. Similiar to the logical and operation, the all()
function returns True if all the values in the given iterable are True
or if an empty iterable is passed, otherwise it returns False
. One of the best features of the all()
function is that it stops the execution as soon as the result is known.Iterable values | all() method return value |
---|---|
All Truth values | True |
All False values | False |
One Truth value and all others False | False |
One False value and all others True | False |
Empty iterable | True |
The all()
method is equivalent to the following code:
def all(iterable):
for element in iterable:
if not element:
return False
return True
Examples:
all() function with Lists:
# all values are true
# non-zero values are considered true
l1 = [5,65,8,12]
print(all(l1))
# all values are false
l2 = [0, False, 0]
print(all(l2))
# one value is false, others are true
l3 = [5,21,3,0,54]
print(all(l3))
# one value is true, others are false
l4 = [True,0,0,False]
print(all(l4))
# empty iterable
l5 = []
print(all(l5))
Output:
True
False
False
False
True
all() function with Strings:
The all()
function always returns a True
value for purely string parameters.
# non-empty string
s1 = 'CodesDope'
print(all(s1))
# non-empty string
s2 = '0'
print(all(s2))
# empty-string
s3 = ''
print(all(s3))
Output:
True
True
True
all() function with Dictionaries:
In case of dictionaries, if all keys (not values) are true or the dictionary is empty, the all()
function returns True
, otherwise, it returns False
.
# all keys are true
# 0 is False
# 1 is True
d1 = {5:'Fri', 6:'Sat', 7:'Sun'}
print(all(d1))
# all keys are false
d2 = {0:'False', False: 0}
print(all(d2))
# one value is false, others are true
d3 = {0:'Red', 1:'Blue',3:'Black'}
print(all(d3))
# one value is true, others are false
d4 = {1:'True',0:'False', False: 0}
print(all(d4))
# empty iterable - no elements
d5 = {}
print(all(d5))
Output:
True
False
False
False
True
all() function with Tuples:
# all values are true
t1 = (8,25,6,4,7)
print(all(t1))
# all values are false
t2 = (0, False, 0)
print(all(t2))
# one value is false, others are true
t3 = (0,2,3,4)
print(all(t3))
# one value is true, others are false
t4 = (0, 0, 1)
print(all(t4))
# empty iterable - no elements
t5 = ()
print(all(t5))
Output:
True
False
False
False
True
That sums up the features of the Python all()
method.