[Numpy-discussion] stumped numpy user seeks help

Keith Goodman kwgoodman at gmail.com
Tue Aug 29 18:09:34 CDT 2006


On 8/29/06, Mathew Yeates <myeates at jpl.nasa.gov> wrote:

> I have an M by N array of floats. Associated with the columns are
> character labels
> ['a','b','b','c','d','e','e','e']  note: already sorted so duplicates
> are contiguous
>
> I want to replace the 2 'b' columns with the sum of the 2 columns.
> Similarly, replace the 3 'e' columns with the sum of the 3 'e' columns.

Make a cumsum of the array. Find the index of the last 'a', last 'b',
etc and make the reduced array from that. Then take the diff of the
columns.

I know that's vague, but so is my understanding of python/numpy.

Or even more vague: make a function that does what you want.




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