[Numpy-discussion] More zaniness Re: simple question

Keith Goodman kwgoodman at gmail.com
Thu Jul 6 16:43:34 CDT 2006


On 7/6/06, Mathew Yeates <myeates at jpl.nasa.gov> wrote:
> okay, I went back to the binary windows distrib. Based on Keths code I wrote
>
>  >> print numpy.asmatrix(all_dates == start_dates[row],dtype=int)
> [[0 0 0 0 0 0 0 0 0 0 0 1 0 0]]
>  >> [row,numpy.asmatrix(all_dates == start_dates[row],dtype=int)] = -1
>  >> print A[row,:]
> [[-1. -1.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.]]
>
> huh? It set the first 2 elements and not the 12'th!!

You are assigning -1 to column 0 thirteen times and assinging -1 to
column 1 once.

For now, until boolean indexing works with matrices, I would just use
brute force:

A[row,where(all_dates.A == 10)[0]]

Or you can do all rows at once with

A[all_dates== 10]

where all_dates is the same size as A.




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