[Solved] python add value to a list when iterate the list

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You iterate over an array which you grow as you iterate over it.

First values is [2,3,4] then after the first iteration, values is [2, 3, 4, [2, 255, 255]] then [2, 3, 4, [2, 255, 255], [3, 255, 255]] etc. You should print along the iteration to understand it better.

The reason is append actually changes the very object you are iterating over. You could try

values = [2,3,4]
new_values = []
for v in values:
    new_values.append([v,255,255])

solved python add value to a list when iterate the list