DOC: Add recipe for shifting groups of values based on the index

[unutbu]

No description provided.

[jreback]

can u put the final df on next line (rather than semi colon it)

[jorisvandenbossche]

I also think this line is misaligned by one space with the initial df = ..

[unutbu]

So edited.

[jreback]

@unutbu thanks!

[jreback]

It think in 0.14 enabled .shift(1) to work directly, rathern than .apply(lambda grp: grp.shift(1))

i'll fixup

[unutbu]

Ah. That works as far back as 0.8.0 as well.

[unutbu]

Just for fun I wanted to use git bisect to find the first commit where groupby(...).shift(1) works. I can do it manually, but this requires that I reinstall pandas to test each commit:

/bin/rm -rf ~/src/pandas/{build,dist} && cdsitepackages && /bin/rm -rf pandas*
cd ~/src/pandas && python setup.py build_ext --inplace && python setup.py install 

I suppose I could write a unittest script with a setUp method which performs the installation, and then run git bisect run .... But is there an easier, automated way?

[jreback]

ahh...that's the automatic function call generation, kind of a syntactic sugar

I don't any easier way to run git bisect....only used it a couple of times.

I think bisect will do the install for you (e.g. it checkouts a particular commit), runs setup, then runs the code....