Check if list contains an element and append to another list's values to a list

Question

I have 3 lists :

A = [32, 33, 54, 66, 67]
B = [33, 4, 67]
C = ['A', 'B', 'C']

What i’m trying to do is that i want to check if for every element in list A is in B, then it should append an element from C by order to a list D, if not, then it should append an empty string, and here is the result i’m looking for :

D = ['', 'A', '', '', 'B']

and here is what i wrote, but i get back a nested list C of all elements inside it in every position where A is in B, so i should also loop for every element in C, can you please tell me how i can do that ?

D = []

for a in A:
    if a in B:
        D.append(C)
    else:
        D.append('')


result: D = ['', [A, B, C], '', '', [A, B, C]]

thank you so much

Asked By: ali alae

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Source

Answer 1

Maybe you can try this code first:

Explain: you want to advance the item in list C if the required condition met. Using the iter is like a pointer to loop and next will go to next item.


expected = ['', 'A', '', '', 'B']

it = iter(C)                     # it's looping C as a pointer

D = []
for x in A:
    if x in set(B):
        D.append(next(it))
    else:
        D.append('')

        
print(D)
# ['', 'A', '', '', 'B'] == expected *result*

Answered By: Daniel Hao

Check if list contains an element and append to another list's values to a list

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