numpy : argmin in multidimensional arrays

[Travis E. Oliphant]

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.


If you give an axis argument, then the minimum is found along the 
specified dimension and you get an N-1 dimensional array of indices that 
will all be between 1 and myarray.shape[axis]


-Travis