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Python | Count true booleans in a list

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  • Last Updated : 25 Jun, 2019

Given a list of booleans, write a Python program to find the count of true booleans in the given list.

Examples:

Input : [True, False, True, True, False]
Output : 3

Input : [False, True, False, True]
Output : 2

 
Method #1 : Using List comprehension

One simple method to count True booleans in a list is using list comprehension.




# Python3 program to count True booleans in a list
  
def count(lst):
  
    return sum(bool(x) for x in lst)
      
# Driver code
lst = [True, False, True, True, False]
print(count(lst))

Output:

3

 
Method #2 : Using sum()




# Python3 program to count True booleans in a list
  
def count(lst):
      
    return sum(lst)
      
# Driver code
lst = [True, False, True, True, False]
print(count(lst))

Output:

3

A more robust and transparent method to use sum is given below.




def count(lst):
      
    return sum(1 for x in lst if x)

 
Method #3 : count() method




# Python3 program to count True booleans in a list
  
def count(lst):
      
    return lst.count(True)
      
# Driver code
lst = [True, False, True, True, False]
print(count(lst))

Output:

3

 
Method #4 : filter()




# Python3 program to count True booleans in a list
  
def count(lst):
      
    return len(list(filter(None, lst)))
      
# Driver code
lst = [True, False, True, True, False]
print(count(lst))

Output:

3

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