How to add modified dictionary into a list without changing the one that is already in that list in python?

Question

I meet a problem when trying to continuously add modified dictionaries into the same list. I simplified what I want to do below:

a = {"1":"1"}
b = [a]

for i in range (2,5):
 a["1"] = i
 b.append(a)

print(b)

This will give me

[{'1': 4}, {'1': 4}, {'1': 4}, {'1': 4}]

But I want b as

[{'1': 1}, {'1': 2}, {'1': 3}, {'1': 4}]

How should I do this?

you need to copy the dict, e.g. `a = dict(a)` in the loop – Chris_Rands Dec 19 '21 at 17:35 — Chris_Rands, Dec 19 '21 at 17:35
alternatively `{"1": i for i in range(1,5)}` – Chris_Rands Dec 19 '21 at 17:38 — Chris_Rands, Dec 19 '21 at 17:38

score 0 · Answer 1 · answered Dec 19 '21 at 17:39

Do not reuse the "a" dict inside the loop and create a new small dict each time it is needed You can do like this:

a = {"1":"1"}
b = [a]

for i in range (2,5):
    b.append({"1":i})

print(b)

the result is :

[{'1': '1'}, {'1': 2}, {'1': 3}, {'1': 4}]

1 Answers1