[Numpy-discussion] indexing question

Neal Becker ndbecker2@gmail....
Mon Jun 21 17:42:19 CDT 2010


Robert Kern wrote:

> On Mon, Jun 21, 2010 at 14:01, Neal Becker <ndbecker2@gmail.com> wrote:
>> Can I find an efficient way to do this?
>>
>> I have a 2d array, A, 80 rows by 880 columns.
>>
>> I have a vector, B, of length 80, with scalar indexes.
> 
> I assume you mean 880.
> 
>> I want a vector output C where
>> C[i] = A[b[i],i] (i=0,879)
> 
> C = A[b, np.arange(880)]
> 

Thanks!  Just what I needed.

I wouldn't have guessed this.  Do we have a wiki to save useful examples 
like this?



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