The problem of python list remove function

Question

I know it is maybe a duplicate question. But due to my poor English expression,I don't know how to search it.

Recently I find a problem in python list.remove,Here is the code:

data = []
for i in range(1000):
    Tempdict = {}
    Tempdict["code"] = str(i)
    data.append(Tempdict)

codes_to_keep = ("1","8","80")
for i in data:
    if not i["code"] in codes_to_keep:
        data.remove(i)

print(data) #{"code":"1","code":"3","code":"5".......},it will keep odd number leave.

Or if I use this to delete number which need to be de:

data = []
for i in range(1000):
    Tempdict = {}
    Tempdict["code"] = str(i)
    data.append(Tempdict)

codes_to_delete = ("1","8","80")
for i in data:
    if i["code"] in codes_to_delete:
        data.remove(i)

print(data) #{"code":"0","code":"2"xxx},This is what I expected

What happened?

I know there is a way to achieve this is to use ``result = list(item for item in data if item["code"] in codes_to_keep)`` — jizhihaoSAMA, Mar 09 '20 at 04:25
you're editing list during iterating over it. Thats not recommended. — Vicrobot, Mar 09 '20 at 04:27

score 0 · Answer 1 · answered Mar 09 '20 at 04:34

0

For the proper answer,

data = []
for i in range(1000):
    Tempdict = {}
    Tempdict["code"] = str(i)
    data.append(Tempdict)


codes_to_keep = ("1","8","80")
# for i in data:
#     if not i["code"] in codes_to_keep:
#         data.remove(i)

data = list(item for item in data if item["code"] in codes_to_keep)

print(data)

[{'code': '1'}, {'code': '8'}, {'code': '80'}]

answered Mar 09 '20 at 04:34

Arun Augustine

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Sure,I know this idea.I have written it in my question comment.But still thanks~ – jizhihaoSAMA Mar 09 '20 at 04:36

The problem of python list remove function

1 Answers1