DOC: clarify behavior of shallow copy with Copy-on-Write in NDFrame docstring #63291
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pandas/core/generic.py
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| the calling object's data or index (only references to the data | ||
| and index are copied). Any changes to the data of the original | ||
| will be reflected in the shallow copy (and vice versa). | ||
| and index are copied). With Copy-on-Write enabled by default, |
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Since CoW can't be disabled, I think we should remove the "enabled by default" bit.
| and index are copied). With Copy-on-Write enabled by default, | |
| and index are copied). With Copy-on-Write, |
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I've removed the phase enabled by default
pandas/core/generic.py
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| changes to the data of the original will *not* be reflected in the | ||
| shallow copy (and vice versa). The shallow copy uses a lazy (deferred) |
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This is true in terms of mutations at the e.g. Series level, but not array.
ser = pd.Series([1, 2, 3])
ser2 = ser.copy(deep=False)
ser.array[1] = 100
print(ser2)
# 0 1
# 1 100
# 2 3
# dtype: int64I'm not sure if we want to highlight this, cc @jorisvandenbossche
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Also not sure if we want to go into the details here, but in any case it would be good to slightly rephrase the "changes to the data of the original will not be reflected .." to "changes to the original will not be reflected .." (i.e. leave out the "the data of").
The above example currently also only works with .array, and not with eg .values (given the current state of #63099)
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I'm actually done with the suggested changes! Please let me know if further improvement is needed...
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closes #63289