U Kv f@sddlZdddZdS)NcCst|tjr|jdkr|j}t|}t|d}|sDt|dj}tj||f|d}d}d}g}g} g} t ||D]N\} } | |dd|f<tj |} | |kr| | | }|d7}qt| | qt|ddd|f|fS)z construct array with independent columns x is either iterable (list, tuple) or instance of ndarray or a subclass of it. If x is an ndarray, then each column is assumed to represent a variable with observations in rows. r)dtypeN) isinstancenpZndarrayndimTlenZasarrayrzeroszipZlinalgZ matrix_rankappend)xvarnamesrZ nvars_origZnobsZxoutcountZrank_oldZ varnames_newZvarnames_droppedZkeepindxxiniZrank_newrs