Python：用相邻的数据点替换列表中的元素

Question

I currently have a list like this:

A = [1, 2, "NaN", 4, 5,"NaN"]

If an element is null, I would like to replace it with the average value of adjacent values so A[3] would be replaced by 3 (2+4/2).

If there is only one adjacent value as shown by A[5], then return the one adjacent value itself.

Desired output:

A = [1, 2, 3, 4, 5, 5]

Answer 1

I'm sure there is a better way, but here is one way to do it. It handles the case where NaN appears at the end of the list.

Code:

A = [1, 2, "NaN", 4, 5,"NaN"]

for i in range(len(A)):
    if A[i] == "NaN":
        if i == 0: A[i] = A[1]
        elif i == len(A) - 1: A[i] = A[i - 1]
        else: A[i] = (A[i - 1] + A[i + 1]) // 2
        
print(A)

Output:

[1, 2, 3, 4, 5, 5]