Add "rows" as option to "axis" docstring

[martin-martin]

The "axis" parameter of pd.concat() can take the string 'rows' as an optional way of explicitly defining the default row axis for concatenation:

import pandas as pd pd.concat([pd.DataFrame(), pd.DataFrame()], axis="rows")

Using 'rows' instead of 'index' or 0 might be more intuitive as a counterpart to 'columns'. In any case, it's a possible option, so it might be helpful to represent that in the docstring.

The proposed update in the docstring uses the suggested format based on pandas docstring guide:
https://pandas.pydata.org/docs/dev/development/contributing_docstring.html#parameter-types

For axis, the convention is to use something like:
axis : {0 or ‘index’, 1 or ‘columns’, None}, default None

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[mroeschke]

Thanks for the pull request.

For consistency, this should be changed everywhere axis is documented and tested as well (for the axis fixture in pandas/conftest.py)

[jreback]

-1 on this change. we have a long history of using index and columns. changing in a single place is a no-no. changing everywhere might be ok, but is going to be quite invasive.

[mroeschke]

Thanks for the pull request but it appears that this change is unlikely to move forward with our pervasive usage of "index". Closing