[Numpy-discussion] [numpy] argmin in multidimensional arrays

Glen W. Mabey Glen.Mabey@swri....
Sat Mar 3 13:46:50 CST 2007


On Thu, 06 Jul 2006 04:59:22 -0600, Travis wrote:
> Subject: numpy : argmin in multidimensional arrays
> 
> TG wrote:
> > Hi there.
> > 
> > I am working with multi-dimensional arrays and I need to get
> > coordinates of the min value in it.
> > 
> > using myarray.argmin() returns the index in the flatten array, which is
> > a first step, but I wonder if it is possible to get the coordinates
> > directly as an array, rather than calculating them myself by using this
> > flat index and the shape of the array.
> > 
> > well, in fact i'm not sure to understand how argmin(myarray) works,
> > when myarray is multidimensional.
> 
> 
> By default, the argmin method flattens the array and returns the flat 
> index.  You can get the corresponding element using
> 
> myarray.flat[index]
> 
> Alternatively, you can use the function unravel_index
> 
> unravel_index(flat_index, myarray.shape)
> 
> to return an N-dimensional index.

<not_a_complaint>

Does anyone else find this behavior counter-intuitive?  

It seems to me that one of the great design features of numpy is the
n-dim generality it provides, and argmin is one function in this breaks
down, IMHO.

</not_a_complaint>

Glen Mabey



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