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Created on 2019-10-12 23:54 by dev40573, last changed 2022-04-11 14:59 by admin. This issue is now closed.
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| File name | Uploaded | Description | Edit | |
| three.py | dev40573, 2019-10-12 23:54 | |||
| Messages (3) | |||
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| msg354558 - (view) | Author: DEVOR BLAKE DANIELS (dev40573) | Date: 2019-10-12 23:54 | |
l=[2,3,4] p=l p[0]=5 when I change p[0] to 5,l[0] is also changed to 5. I use slicing to get around this ,but when dealing with lists like s[][],slicing does not work |
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| msg354560 - (view) | Author: Pablo Galindo Salgado (pablogsal) *  |
Date: 2019-10-13 00:41 | |
Hi Devor, This is not a bug in Python but indeed documented behavior. When you do p=l you are creating a new reference to the same list ([2,3,4]), so changing one changes the other. If you want to make a copy you can do p = l.copy() |
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| msg354561 - (view) | Author: Steven D'Aprano (steven.daprano) * |
Date: 2019-10-13 00:44 | |
This is not a bug, it is part of the design of the language. Assignment in Python does not make a copy of lists, or any other object. In your sample code, p and l are two names for the same list, like "Devor Blake Daniels" and "dev40573" are two names for the same person (you). You can use slicing to make a copy of the list, or the copy module, or the list constructor. I don't understand your comment "when dealing with lists like s[][],slicing does not work". |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:59:21 | admin | set | github: 82639 |
| 2019-10-13 00:45:55 | steven.daprano | set | nosy:
+ pablogsal |
| 2019-10-13 00:44:16 | steven.daprano | set | nosy:
+ steven.daprano messages: + msg354561 |
| 2019-10-13 00:41:44 | pablogsal | set | nosy:
- pablogsal |
| 2019-10-13 00:41:09 | pablogsal | set | status: open -> closed nosy: + pablogsal messages: + msg354560 resolution: not a bug stage: resolved |
| 2019-10-12 23:54:11 | dev40573 | create | |