Python | Indices of N largest elements in list

Sometimes, while working with Python lists, we can have a problem in which we wish to find N largest elements. This task can occur in many domains such as web development and while working with Databases. We might sometimes, require to just find the indices of them. Let’s discuss certain way to find indices of N largest elements in list.

Method : Using sorted() + lambda + list slicing
This task can be performed using the combination of above functions. In this the sorted(), can be used to get the container in way which requires to get N largest elements at rear end and then the indices can be computed using list slicing.

# Python3 code to demonstrate working of 
# Indices of N largest elements in list 
# using sorted() + lambda + list slicing 
  
# initialize list 
test_list = [5, 6, 10, 4, 7, 1, 19] 
  
# printing original list 
print("The original list is : " + str(test_list)) 
  
# initialize N  
N = 4
  
# Indices of N largest elements in list 
# using sorted() + lambda + list slicing 
res = sorted(range(len(test_list)), key = lambda sub: test_list[sub])[-N:] 
  
# printing result 
print("Indices list of max N elements is : " + str(res)) 

Output :

The original list is : [5, 6, 10, 4, 7, 1, 19]
Indices list of max N elements is : [1, 4, 2, 6]

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