HarlanH/JuliaData — pull request #46 by doobwa (2012-08-06 15:58:46+00:00)
Title: Allow column groups in formulas.

Small update to add functionality to formulas so that one can use column groups inside formulas. For example `y ~ odd_predictors * x2` will interact all of the column in the `odd_predictors` group with the column `x2`.

I added some helper functions (e.g. `hcat` for `Array{DataFrame,1}`).

Please let me know if the tests pass or if you see improvements that can be made.