[Numpy-discussion] Selecting columns of a matrix

Alan G Isaac aisaac at american.edu
Wed Jun 21 21:08:50 CDT 2006

> Alan G Isaac wrote: 
>> M.transpose()[V>0] 
>> If you want the columns as columns, 
>> you can transpose again. 

On Wed, 21 Jun 2006, Keith Goodman apparently wrote: 
> I can't get that to work when M is a n by m matrix: 

The problem is not M being a matrix.
You made V a matrix (i.e., 2d).
So you need to ravel() it first.
>> M.transpose()[V.ravel()>0] 

Alan Isaac

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