Python | Find all elements count in list

Getting the length of list is quite common problem and has been dealt with and discussed many times, but sometimes, we require to better it and find total number of elements, i.e. including those of nested list as well. Let’s try and get the total count and solve this particular problem.

Method #1 : Using list comprehension + len()
We can solve this problem using the list comprehension as a potential shorthand to the conventional loops that we may use to perform this particular task. We just iterate and count the nested list and at end return the cumulative count using len function.

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# Python3 code to demonstrate
# count of all the elements in list 
# Using list comprehension
  
# initializing list
test_list = [[1, 4, 5], [7, 3], [4], [46, 7, 3]]
  
# printing original list
print("The original list : " + str(test_list))
  
# using list comprehension
# count of all the elements in list
res = len([ele for sub in test_list for ele in sub])
  
# print result
print("The total element count in lists is : " + str(res))

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Output :

The original list : [[1, 4, 5], [7, 3], [4], [46, 7, 3]]
The total element count in lists is : 9

 

Method #2 : Using chain() + len()
This particular problem can also be solved using the chain function instead of list comprehension in which we use the conventional len function to check the lengths.

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# Python3 code to demonstrate
# count of all the elements in list 
# Using chain() + len()
from itertools import chain
  
# initializing list
test_list = [[1, 4, 5], [7, 3], [4], [46, 7, 3]]
  
# printing original list
print("The original list : " + str(test_list))
  
# using chain() + len()
# count of all the elements in list
res = len(list(chain(*test_list)))
  
# print result
print("The total element count in lists is : " + str(res))

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Output :

The original list : [[1, 4, 5], [7, 3], [4], [46, 7, 3]]
The total element count in lists is : 9


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