[Numpy-discussion] On responding to dubious ideas (was: Re: Advanced indexing: "fancy" vs. orthogonal)

[Alan G Isaac]

On 4/9/2015 11:26 PM, Alexander Belopolsky wrote:
>     > but if I try to do both, I get the diagonal instead
>     >
>     > >>> a[[1,2],[1,2]]
>     > array([22, 33])
>     >


> On Thu, Apr 9, 2015 at 8:41 PM, Derek Homeier <derek at astro.physik.uni-goettingen.de <mailto:derek at astro.physik.uni-goettingen.de>> wrote:
>     a[1:3,1:3]?
>     Can’t be generalised to arbitrary selections of rows,columns, though (e.g. a[1::2,::2] still works…)



On 4/9/2015 11:26 PM, Alexander Belopolsky wrote:
> I am interested in the arbitrary selection of rows and columns given by indices or by boolean selectors.



You mean like this?
import numpy as np
a = np.arange(20).reshape((4,5))
rows = [0,3]
cols = [1,2,4]
print a[rows][:,cols]

Alan Isaac