[Docs] GroupsBy Example: Group by value of sum of columns

[mazieres]

Hi,
TomAugspurger suggested me on StackOverFlow to suggest this example of df.groupby() here for being considered as relevant to add to the docs. The idea was to determine a way to regroup columns of a DataFrame according to their sum, and to sum the aggregated ones.

In [1]: import pandas as pd

In [2]: dat = {'a':[1,0,0], 'b':[0,1,0], 'c':[1,0,0], 'd':[2,3,4]}

In [3]: df = pd.DataFrame(dat)

In [4]: df
Out[4]: 
   a  b  c  d
0  1  0  1  2
1  0  1  0  3
2  0  0  0  4

In [5]: df.groupby(df.sum(), axis=1).sum()
Out[5]: 
   1  9
0  2  2
1  1  3
2  0  4

[jreback]

sure....want to try to add in via a pull-request, see here: http://pandas.pydata.org/pandas-docs/dev/contributing.html

[mazieres]

Sure, i'll suggest a way to add it to the docs via PullRequest. Thanks.

[TomAugspurger]

Great thanks. It should go under doc/source/groupby.rst.

[mazieres]

OK, but The file you indicated misses most of the code snippet available at http://pandas.pydata.org/pandas-docs/dev/groupby.html, and I couldn't figure out where there are called from. Any hint ?

[jorisvandenbossche]

I don't know exactly what you mean, but: (a) github does not render the rst files with code very well. So if you just look at https://github.com/pydata/pandas/blob/master/doc/source/groupby.rst you won't see the code snippets (but it you go to -> 'raw' or when you open it locally, you will see the code snippets) and (b) the code snippets in the docs only contain the code itself, and not the output as you see it on the html pages. This is because during the doc building all code snippets are run and the output generated and saved in the html (see explanation here: http://pandas.pydata.org/pandas-docs/stable/contributing.html#contributing-to-the-documentation)