ENH: Remove for loop from DataFrame.update() #56303
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phofl
requested changes
Dec 2, 2023
| for col in self.columns.intersection(other.columns): | ||
| this = self[col]._values | ||
| that = other[col]._values | ||
| cols = self.columns.intersection(other.columns) |
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Calling ._values on multiple columns converts to a common dtype for all columns, probably object as soon as you have non-numeric columns. This is terrible from a performance perspective, so doing this at once is actually a lot slower in real world use cases than doing one column at a time
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Ah, understood. Thank you for taking the time to explain.
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It's not clear to me why
DataFrame.update()needs to perform the update one column at a time.I'd be interested to get any feedback on this, and if it's of interest I can think through any edge cases and add some more tests etc.
(this is my first contribution to the actual code, rather than docs, so if I'm missing something obvious please let me know!)
Thanks!
doc/source/whatsnew/vX.X.X.rstfile if fixing a bug or adding a new feature.