CoW warning mode: setting values into single column of DataFrame #56020
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|
Green! |
| if not using_cow: | ||
| # Normally would need to do this before, but | ||
| # numpy only returns same array when round operation | ||
| # is no-op | ||
| # https://github.com/numpy/numpy/blob/486878b37fc7439a3b2b87747f50db9b62fea8eb/numpy/core/src/multiarray/calculation.c#L625-L636 | ||
| values = values.copy() | ||
| else: | ||
| refs = self.refs |
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We were incorrectly adding forwarding refs always, even when we did make a copy. For CoW this doesn't cause anything wrong, but for the warning mode this gave false positive warnings.
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Yeah sorry for that, I didn't care much about non CoW when adding all of those
phofl
reviewed
Nov 17, 2023
| df = DataFrame({"a": [1, 2, 3], "b": 1, "c": 1}) | ||
| view = df[:] | ||
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| df["b"] = 100 | ||
| arr = get_array(df, "a") | ||
| view = None # noqa: F841 | ||
| df.iloc[0, 0] = 100 | ||
| # TODO(CoW-warn) false positive? |
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Yeah, comment explaining this is 3 lines below
phofl
approved these changes
Nov 17, 2023
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Next subtask of #56019.
This tackles
mgr.column_setitem, which is used to set values into a single column (but not setting the full column, so likedf.loc[idx, "col"] = ..)