statsmodels.sandbox.regression.try_ols_anova.
data2proddummy
creates product dummy variables from 2 columns of 2d array
drops last dummy variable, but not from each category singular with simple dummy variable but not with constant
quickly written, no safeguards
statsmodels.sandbox.regression.try_ols_anova.data2groupcont
statsmodels.sandbox.regression.try_ols_anova.dropname