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Python – Find Product of Index Value and find the Summation

  • Last Updated : 02 Dec, 2020

Given a List of elements, write a Python program to perform the product of index and value and compute the summation.

Examples:

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Input : test_list = [5, 3, 4, 9, 1, 2] 
Output : 76 
Explanation : 5 + (3*2) 6 + 12 + 36 + 5 + 12 = 76
 



Input : test_list = [5, 3, 4] 
Output : 23 
Explanation : 5 + (3*2) 6 + 12 = 23 

Method #1: Using loop + enumerate()

In this, we iterate for each element along with its index using enumerate() and compute the product. Sum counter is maintained to update the intermediate sum of the product computed.

Python3




# Python3 code to demonstrate working of
# Index Value Product Sum
# Using loop + enumerate()
  
# initializing list
test_list = [5, 3, 4, 9, 1, 2]
  
# printing original list
print("The original list is : " + str(test_list))
  
res = 0
for idx, ele in enumerate(test_list):
  
    # updating summation of required product
    res += (idx + 1) * ele
  
# printing result
print("The computed sum : " + str(res))
Output
The original list is : [5, 3, 4, 9, 1, 2]
The computed sum : 76

Method #2 : Using sum() + list comprehension + enumerate()

One liner way to solve this problem, in this, we perform task of getting products iteration as list comprehension and summation at end is done using sum().

Python3




# Python3 code to demonstrate working of
# Index Value Product Sum
# Using loop + enumerate()
  
# initializing list
test_list = [5, 3, 4, 9, 1, 2]
  
# printing original list
print("The original list is : " + str(test_list))
  
# one liner to solve problem using list comprehension
res = sum([(idx + 1) * ele for idx, ele in enumerate(test_list)])
  
# printing result
print("The computed sum : " + str(res))
Output
The original list is : [5, 3, 4, 9, 1, 2]
The computed sum : 76



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