MAINT: Optimize loadtxt usecols. #19618
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eric-wieser
reviewed
Aug 6, 2021
eric-wieser
reviewed
Aug 6, 2021
numpy/lib/npyio.py
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| if usecols: | ||
| vals = [vals[j] for j in usecols] | ||
| if len(vals) != ncols: | ||
| vals = usecols_getter(vals) | ||
| elif len(vals) != ncols: |
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Can you explain this change to an elif?
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If usecols is not None, then we already know that usecols_getter will (by construction) return a list with the right number of elements. The performance gain is negligible, but it seems just good to skip the unneeded check.
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@anntzer Needs rebase. |
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rebased |
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This was referenced Aug 17, 2021
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charris
reviewed
Aug 22, 2021
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#19693 is in, everything needs a rebase :) |
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7-10% speedup in usecols benchmarks; it appears that even in the single-usecol case, avoiding the iteration over `usecols` more than compensates the cost of the extra function call to usecols_getter.
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Thanks @anntzer . |
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7-10% speedup in usecols benchmarks; it appears that even in the
single-usecol case, avoiding the iteration over
usecolsmore thancompensates the cost of the extra function call to usecols_getter.