pydata/pandas — pull request #2561 by jreback (2012-12-18 23:06:59+00:00)
Title: ENH: added support for data column queries 

- can construct searches on the actual columns of the data
e.g. store.select('df_dc',[ Term('B>0'), Term('string=foo') ])
(where B and string are columns in the frame)

- added nan_rep for supporting string columns with nan's in them
- performance enhancements on string columns
- more tests & docs for data columns