CODEWITHSUNDEEP
pythonlistcasting
zephyr
zephyr

Reputation: 1900

python List typecasting and setting values

I was trying this out 

>>> x = [[1, 2, 3], 10.5]
>>> z = list(x)
>>> z[1] = 10.6
>>> z
[[1, 2, 3], 10.6]
>>> x
[[1, 2, 3], 10.5]
>>> z[0][2] = 5
>>> z
[[1, 2, 5], 10.6]
>>> x
[[1, 2, 5], 10.5]

Why the change is being reflected in x[0][2] ? and similarly not in x[1]???

Upvotes: 1

Views: 44

Answers (1)

Maciej Gol
Maciej Gol

Reputation: 15854

The list(x) created a new top-level list thus changing its top-level values - like 10.5 - won't propagate to x. On the other hand, the inner list is a reference thus changes to it are shared amongst all containers containing it because they all contain the very same object. If you would like a separate copy of x, use copy.deepcopy.

Upvotes: 2

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