Python | Add list elements with a multi-list based on index

Last Updated : 22 May, 2019

Given two lists, one is a simple list and second is a multi-list, the task is to add both lists based on index.

Example:

Input:
List = [1, 2, 3, 4, 5, 6]
List of list = [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]

Output:
[[1], [2, 3, 4], [3, 4], [4, 5], [5, 6, 7], [6]]

Explanation:
[1] = [1+0]
[2, 3, 4] = [0+2, 1+2, 2+2]
[3, 4] = [3+0, 3+1]
[4, 5] = [4+0, 4+1]
[5, 6, 7] = [5+0, 5+1, 5+2]
[6] = [6+0]

Let’s discuss some methods to do this task.

Method #1: Using iteration

# Python code to add list elements 
# with a multi-list based on index 
  
# List initialization
List = [1, 2, 3, 4, 5, 6]
List_of_List = [[0], [0, 1, 2], [0, 1],
                [0, 1], [0, 1, 2], [0]]
Output = []
  
# Iteration 
for x in range(len(List)):
    temp = []
    for y in List_of_List[x]:
        temp.append(y + List[x])
    Output.append(temp)
  
# Printing
print("Initial list is:", List)
print("Initial list of list is :", List_of_List)
print("Output is", Output)

Output:

Initial list is: [1, 2, 3, 4, 5, 6]
Initial list of list is : [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output is [[1], [2, 3, 4], [3, 4], [4, 5], [5, 6, 7], [6]]

Method #2: Using enumerate()

# Python code to add list elements 
# with a multi-list based on index
  
# List initialization
List = [1, 2, 3, 4, 5, 6]
List_of_List = [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output = []
  
# using enumerate 
Output = [[elem + List[x] for elem in y] 
          for x, y in enumerate(List_of_List)]
  
  
# Printing
print("Initial list is:", List)
print("Initial list of list is :", List_of_List)
print("Output is", Output)

Output:

Initial list is: [1, 2, 3, 4, 5, 6]
Initial list of list is : [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output is [[1], [2, 3, 4], [3, 4], [4, 5], [5, 6, 7], [6]]

Method #3: Using Zip()

# Python code to add list elements 
# with a multi-list based on index
  
# List initialization
List = [1, 2, 3, 4, 5, 6]
List_of_List = [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output = []
  
# using zip 
Output = [[z + x for z in y ]for x, y in
                 zip(List, List_of_List)]
  
# Printing
print("Initial list is:", List)
print("Initial list of list is :", List_of_List)
print("Output is", Output)

Output:

Initial list is: [1, 2, 3, 4, 5, 6]
Initial list of list is : [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output is [[1], [2, 3, 4], [3, 4], [4, 5], [5, 6, 7], [6]]

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Python | Add list elements with a multi-list based on index