Why does x[0].append(4) affects on y[0]?
from copy import copy
x = [[1], [2]]
y = copy(x)
x.append([3])
x[0].append(4)
print(x)
print(y)
>>> [[1, 4], [2], [3]]
>>> [[1, 4], [2]]
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4because its a shallow copy and not deep copy, so only outer most list will be copied and the inner references will be passed as is https://www.geeksforgeeks.org/copy-python-deep-copy-shallow-copy/ – saurabh baid Sep 24 '21 at 18:20
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@saurabhbaid, I want to find out why deepcopy will change something – wowonline Sep 24 '21 at 18:23
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@saurabhbaid, I've got it, thank you – wowonline Sep 24 '21 at 18:25