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PyTables enhancements for selection #1996
changes to pandas.io.pytables to support more natural selection (from tables):
rather than existing
not sure that pandas should get really fancy just yet with operations - (e.g. 'or' operations, and actual value selection)
but probably necessary once pandas support 'chunking' type operations on pytables
need to build a full-fledged selection parser to translate to the numexpr type operations (maybe with a patsy backend????)
not sure of use cases here though - I usually just read in 'about' what data I need and sub-select from there
This was referenced
Nov 15, 2012
referenced this issue
Nov 24, 2012
The theory is to accept a numpy-like DSL (but with frames/series/constants) that potentially need alignment and then pass the numpified to
Which is also similar to the expressions in
a bit non-trivial as to have to take the string expression, compile/parse it, walk the ast tree to find the aligning sections, then repackage to numexpr
@hayd up for it????
Do you think going via Terms is a good solution:
and then the eval'd string would be parsed into that.
That way, we could first get select working with Terms (which shouldn't be too bad), and then write the parser for the DSL (we have to come to a consensus on the grammar...). ?
That is definitely a good start on it. The thoughts I had were:
Roughty equivalent to:
which is an easy way to compose (not that user friendly though),
This then could replace the syntax in
want to give it a try?