[Numpy-discussion] Indices of min/max element of an array?

Christos Siopis christos.siopis at ulb.ac.be
Tue Dec 6 12:29:04 CST 2005


On Tue, Dec 06, 2005 at 12:17:14PM -0500, Perry Greenfield wrote:

> Why not:
> 
> ind = where(arr == arr.max())
> 
> and use the first element of the index array(s)

Thanks, that worked nice! I was stuck with the old Numeric definition of where(). 
Could it perhaps be made more obvious in numarray's where() documentation that it 
can also be called with one parameter only? (I.e., put this information in the 
section header, not mid-way in the description). I'm looking at the April 20, 2005 
documentation release.

Would it be safe to assume that the numarray definition of where() will be the one 
propagated into scipy.core?

As a side note, i am wondering if there is a semantic asymmetry in using min() and 
max() to signify the min/max element in the entire array while argmin() and 
argmax() signify the min/max element along each axis. At the same time, and as far 
as i can tell, there is no min()/max() method to provide the min/max element along 
each axis, and there is no method to do the equivalent of "argmin/max_all()", as 
implemented by where(arr == arr.min/max()). Apologies if this has been discussed 
before.

Thank you,
Christos




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