Python | Add list elements with a multi-list based on index
Last Updated :
17 Apr, 2023
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
Python3
List = [1, 2, 3, 4, 5, 6]
List_of_List = [[0], [0, 1, 2], [0, 1],
[0, 1], [0, 1, 2], [0]]
Output = []
for x in range(len(List)):
temp = []
for y in List_of_List[x]:
temp.append(y + List[x])
Output.append(temp)
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]]
Time Complexity: O(n*n) where n is the number of elements in the list
Auxiliary Space: O(n), where n is the number of elements in the new output list
Method #2: Using enumerate()
Python3
List = [1, 2, 3, 4, 5, 6]
List_of_List = [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output = []
Output = [[elem + List[x] for elem in y]
for x, y in enumerate(List_of_List)]
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]]
Time Complexity: O(n*n), where n is the length of the list test_list
Auxiliary Space: O(n) additional space of size n is created where n is the number of elements in the res list
Method #3: Using Zip()
Python3
List = [1, 2, 3, 4, 5, 6]
List_of_List = [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output = []
Output = [[z + x for z in y ]for x, y in
zip(List, List_of_List)]
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]]
Time Complexity: O(n*n), where n is the length of the list test_list
Auxiliary Space: O(n) additional space of size n is created where n is the number of elements in the list
Method #4: Using map()
In this code, we are using the map() function to add the corresponding elements of the two lists, List and List_of_List. The map() function applies the lambda function on each element of the two lists, which adds the element of List to each element of the sublists in List_of_List.
The lambda function has two parameters, x and y, which represent the current element of List and the current sublist of List_of_List, respectively. The lambda function returns a new list which is the sublist of List_of_List with each element incremented by the corresponding element of List.
Finally, the map() function is wrapped in a call to list() to convert the map object returned by map() into a list.
Python3
List = [1, 2, 3, 4, 5, 6]
List_of_List = [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output = []
Output = list(map(lambda x, y: [z + x for z in y], List, List_of_List))
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]]
The time complexity of this approach is O(n), where n is the length of the lists. The auxiliary space is also O(n), as we are creating a new list of the same size as the original lists.
Method #5: Using nested list comprehension
Python3
List = [1, 2, 3, 4, 5, 6]
List_of_List = [[0], [0, 1, 2], [0, 1],
[0, 1], [0, 1, 2], [0]]
Output = [[y + List[x] for y in sublist] for x, sublist in enumerate(List_of_List)]
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]]
Time Complexity: O(n)
Auxiliary Space: O(n)
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