Philip Kiely philipkiely
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philipkiely
/ weirdpythonbehavior.py
Last active
June 16, 2020 19:03
A quick explanation of a python bug to watch out for
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| # When working with nested lists created with []*x, watch out for this bug: | |
| a = [[0, 0, 0], [0, 0, 0], [0, 0, 0]] | |
| a[0][1] += 1 | |
| print(a) | |
| # gives [[0, 1, 0], [0, 0, 0], [0, 0, 0]] | |
| # totally straightforward! but … | |
| a = [[0]*3]*3 | |
| a[0][1] += 1 | |
| print(a) | |
| # gives [[0, 1, 0], [0, 1, 0], [0, 1, 0]] |
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