numpy.where

Lou Pecora pecora at anvil.nrl.navy.mil
Thu Apr 9 15:09:18 CEST 2009


In article <mailman.3576.1239266409.11746.python-list at python.org>,
 Neil Crighton <neilcrighton at gmail.com> wrote:

> 
> I'm not sure exactly what you're trying to do, but maybe you want a boolean
> array to select the right elements? So if time and energy are 1-d numpy arrays
> of the same length:
> 
> >>> condition = (min_time <= time) & (time <= max_time)
> >>> new_time = time[condition]
> >>> new_energy = energy[condition]
> 
> There's also a Numpy list for these kind of questions:
> 
> http://dir.gmane.org/gmane.comp.python.numeric.general
> 
> Neil


Thanks, Neil.  Always something to learn.  I've used Numpy for several 
years, but still have not plumbed the depths.  Just tried this script 
and, yep, it works.

      arr=array([-1,1.0,2.2,-10.0,1.1, 0.9,-0.9])
      cond= arr < 1.0
      print cond
      brr=arr[cond]
      print brr

Output:

[ True False False  True False  True  True]
[ -1.  -10.    0.9  -0.9]

Really,  I've gotta RTFM. :-)

-- 
-- Lou Pecora



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