fixed conversion to sparse for non-numeric index
this fixes  #11633

this fix breaks some sparse tests,
stuck on `test_combine_first` : `ValueError: total size of new array must be unchanged`

this looks reasonable. I think you may have to adjust some tests, and maybe some more fixing of the dtype propogation.
 I fixed one test to its original state (accounting for conversion of integer values to floats with `to_sparse`). Now `./test_sparse.py` runs OK. 
 can you rebase when you have a chance.
 rebased
 need some tests for this.
 I added a test. 
One existing test fails now.
 The current fix still does not completely solve the problem of sparse pivot #11633 (it uses sparse as input, but produces a dense output). One will need to look into `pivot_table` itself to see if one can make it spit out a sparse table.
 @DSLituiev that's ok, let's get this bug fix in, then can work on that (which is a bit more complicated). _you_ can always start constructing a fix based on THIS branch if you would like.
 @DSLituiev can you update?
 @DSLituiev can you update, lots of Sparse changes recently.
 I'll have a look

On Sat, Apr 9, 2016 at 8:05 AM, Jeff Reback notifications@github.com
wrote:

> @DSLituiev https://github.com/DSLituiev can you update, lots of Sparse
> changes recently.
> 
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> https://github.com/pydata/pandas/pull/11856#issuecomment-207804337
 can you rebase/update
 can you rebase / update, we've had lots of sparse changes.
 As it is important for #667, I've prepared #13201.
 superseded by #13021 
