[Numpy-discussion] Remove duplicate columns

Hi, Is there a way to sort the columns in an array? I need to sort it so that I can easily go through and keep only the unique columns. ndarray.sort(axis=1) doesn't do what I want as it destroys the relative ordering between the various columns. For example, I would like: [[2,1,3], [3,5,1], [0,3,1]] to go to: [[1,2,3], [5,3,1], [3,0,1]] (swap the first and second columns). So I want to treat the columns as objects and sort them. I can do this if I convert to a python list, but I was hoping to avoid doing that because I ultimately need to do element-wise bitwise operations. Thanks!