将一维数组的元素插入到二维数组中的特定位置

Question

Attempting to combine 1 & 2 dimensional list/arrays containing strings using the insert() method.

However getting a specific element from the 1D list and placing that into a specific location within the 2D list is where Im stuck.

Here is a simplified version of what the goal is;

#2D list/array
list1= [['a1','b1'], ['a2','b2'] , ['a3','b3']]

#1D list/array
list2= ['c3','c2','c1']

#desired output
list1= [['a1','b1','c1'], ['a2','b2','c2'] , ['a3','b3','c3']]

Here is the isolated block of code from the script which Im trying to attempt this with;

#loop through 1D list with a nested for-loop for 2D list and use insert() method.
#using reversed() method on list2 as this 1D array is in reverse order starting from "c3 -> c1"
#insert(2,c) is specifying insert "c" at index[2] location of inner array of List1

for c in reversed(list2):
    for letters in list1:
        letters.insert(2,c)

print(list1)

output of the code above;

[['a1', 'b1', 'c3', 'c2', 'c1'], ['a2', 'b2', 'c3', 'c2', 'c1'], ['a3', 'b3', 'c3', 'c2', 'c1']] 

What is the best & most efficient way to go about returning the desired output? Should I use the append() method rather than insert() or should i introduce list concatenation before using any methods?

Any insight would be appreciated!

Answer 1

As discussed in the comments, you can achieve this via a list comprehension using enumerate or zip . You can use enumerate to get the index and sublist from list1 , using the index to select the appropriate value from list2 to append to each sublist:

list1 = [l1 + [list2[-i-1]] for i, l1 in enumerate(list1)]

or you can zip together list1 and the reversed list2 :

list1 = [l1 + [l2] for l1, l2 in zip(list1, list2[::-1])]

Or you can just use a simple for loop to modify list1 in place:

for i in range(len(list1)):
    list1[i].append(list2[-i-1])

For all of these the output is:

[['a1', 'b1', 'c1'], ['a2', 'b2', 'c2'], ['a3', 'b3', 'c3']]