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Created on 2021-03-21 14:45 by haowenqi.zz, last changed 2022-04-11 14:59 by admin. This issue is now closed.
| Messages (4) | |||
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| msg389230 - (view) | Author: Wen Hao (haowenqi.zz) | Date: 2021-03-21 14:45 | |
>>>mat = [[0]*4]*4 >>> mat [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]] >>> mat[1][2]=1 >>> mat [[0, 0, 1, 0], [0, 0, 1, 0], [0, 0, 1, 0], [0, 0, 1, 0]] |
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| msg389233 - (view) | Author: Vedran Čačić (veky) * | Date: 2021-03-21 15:19 | |
All three words in the title are wrong. :-D |
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| msg389243 - (view) | Author: Karthikeyan Singaravelan (xtreak) *  |
Date: 2021-03-21 16:14 | |
By using * 4 in the end you are making four lists having same reference. Hence change in one causes change in other 4 lists. Relevant FAQ : https://docs.python.org/3/faq/programming.html#how-do-i-create-a-multidimensional-list |
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| msg389245 - (view) | Author: John Cena (crazyguyx4) | Date: 2021-03-21 16:21 | |
You are actually creating 4 references to the same list(See the ending *4). This is how python behaves. See the below link as well https://stackoverflow.com/questions/240178/list-of-lists-changes-reflected-across-sublists-unexpectedly |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:59:43 | admin | set | github: 87747 |
| 2021-03-21 16:21:52 | crazyguyx4 | set | nosy:
+ crazyguyx4 messages: + msg389245 |
| 2021-03-21 16:20:11 | rhettinger | set | status: open -> closed resolution: not a bug stage: resolved |
| 2021-03-21 16:14:25 | xtreak | set | nosy:
+ xtreak messages: + msg389243 |
| 2021-03-21 15:19:37 | veky | set | nosy:
+ veky messages: + msg389233 |
| 2021-03-21 14:45:47 | haowenqi.zz | create | |