# [Numpy-discussion] Are there command similar as Matlab find command?

frank wang f.yw@hotmail....
Mon Sep 29 20:16:14 CDT 2008

```Thanks for the help.

It seems that the where command has problem when I tried to run it in the debug mode. It does not return any thing such as:

(Pdb) aa=array([1,2,3,4]
(Pdb) where(aa>2)
(Pdb)

It does not return any result.

Frank> Date: Mon, 29 Sep 2008 16:48:23 -0500> From: oliphant@enthought.com> To: numpy-discussion@scipy.org> Subject: Re: [Numpy-discussion] Are there command similar as Matlab find command?> > frank wang wrote:> > Hi,> > > > I am trying to find a command in numpy or python that perform similar > > function as Matlab find command. It will return the indexes of array > > that satisfy a condition. So far I have not found anything.> > There are several ways to do this, but what are you trying to do? > Non-zero on the boolean array resulting from the condition is the most > direct way:> > (a>30).nonzero()> where(a>30)> > This returns a tuple of indices of length nd, where nd is the number of > dimensions of a. (i.e. for 1-d case you need to extract the first > element of the tuple to get the indices you want).> > But, if you are going to use these indices to access elements of the > array, there are better ways to do that:> > a[a>30]> compress(a>30, a)> > etc.> > -Travis> > _______________________________________________> Numpy-discussion mailing list> Numpy-discussion@scipy.org> http://projects.scipy.org/mailman/listinfo/numpy-discussion
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