[DOCS] Add example of how to preserve order of columns with usecols. #19746
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@@ Coverage Diff @@
## master #19746 +/- ##
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+ Coverage 91.58% 91.6% +0.02%
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Files 150 150
Lines 48862 48864 +2
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+ Hits 44750 44763 +13
+ Misses 4112 4101 -11
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doc/source/io.rst
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| Element order is ignored, so ``usecols=[0, 1]`` is the same as ``[1, 0]``. | ||
| Element order is ignored, so ``usecols=[0, 1]`` is the same as ``[1, 0]``. Element | ||
| order is ignored, so usecols=[1,0] is the same as [0,1]. To instantiate a | ||
| DataFrame with element order preserved use ``pd.read_csv(usecols=[0, 1])[[0, 1]]`` |
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it should be “pd.read_csv(usecols=[0, 1])[[1, 0]]” ？
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Thanks for catching that. Fixed in commit f137bd0
doc/source/io.rst
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| @@ -136,7 +136,11 @@ usecols : array-like or callable, default ``None`` | |||
| that correspond to column names provided either by the user in `names` or | |||
| inferred from the document header row(s). For example, a valid array-like | |||
| `usecols` parameter would be ``[0, 1, 2]`` or ``['foo', 'bar', 'baz']``. | |||
| Element order is ignored, so ``usecols=[0, 1]`` is the same as ``[1, 0]``. | |||
| Element order is ignored, so ``usecols=[0, 1]`` is the same as ``[1, 0]``. Element | |||
| order is ignored, so usecols=[1,0] is the same as [0,1]. To instantiate a | |||
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Could you put these usecols=[] in double back ticks as well? And commas between the elements.
Finally, I have a slight preference for using names like ['foo', 'bar'] instead of [0, 1], even though it's a bit longer.
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Done. Please refer to f137bd0
I went ahead and encased usecols in double back ticks.
Updated column names per your suggestion. I was originally trying to keep consistent with the line before Element order is ignored, so usecols=[0, 1] is the same as [1, 0].
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Hello @EricChea! Thanks for updating the PR. Cheers ! There are no PEP8 issues in this Pull Request. 🍻 Comment last updated on February 18, 2018 at 18:27 Hours UTC |
…mes from numeric to string.
doc/source/io.rst
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| @@ -136,7 +136,12 @@ usecols : array-like or callable, default ``None`` | |||
| that correspond to column names provided either by the user in `names` or | |||
| inferred from the document header row(s). For example, a valid array-like | |||
| `usecols` parameter would be ``[0, 1, 2]`` or ``['foo', 'bar', 'baz']``. | |||
| Element order is ignored, so ``usecols=[0, 1]`` is the same as ``[1, 0]``. | |||
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can you add a blank line before the additions.
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Sure thing. Please refer to 68efc4b
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ping @jreback @jorisvandenbossche : this is green and ready to merge |
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Thanks @EricChea! |
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Thanks for reviewing @TomAugspurger |
…andas-dev#19746) * Add example of how to preserve order of columns with usecols. * Encase usecols in double back ticks for consistency. Change column names from numeric to string. * Add line to separate examples.
What's this PR do?
Adding an example of how to preserve order when using the
usecolsparameter. I've noticed that some folks are still unaware that the columns will not necessarily be returned in the specified order passed tousecols.