[Pandas-dev] Help replacing workflows that used DataFrame.select

[Joris Van den Bossche]

Hi Paul,

That's a good question. I think you can do it with a lambda function, like
this:

(data.
     ... (full pipeline)
     .loc[:, lambda df: complex_fxn_that_selects_a_few_cols(df.columns)]
)

Does that work?

But personally I am not sure if I find this really an usability improvement
compared to the select method.

Best,
Joris



2017-11-28 2:21 GMT+01:00 Paul Hobson <pmhobson at gmail.com>:

> Hey folks,
>
> I noticed that DataFrame.select is now deprecated in favor of
> DataFrame.loc[index.map(selector_fxn)]
>
> PR: https://github.com/pandas-dev/pandas/pull/17633
> Issue: https://github.com/pandas-dev/pandas/issues/12401
>
> I have a lot of work flows that look something like this:
>
>     res = (
>         data.resample(freq)
>             .agg(agg_dict)
>             .pipe(fxn_that_adds_many_cols)
>             .select(complex_fxn_that_selects_a_few_cols, axis='columns')
>     )
>
> It's not immediately clear to me how to access all of the e.g., columns in
> the middle or at the end of a chain of dataframe operations.
>
> Any tips?
>
> -Paul
>
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