[Tutor] Finding the minimum value in a multidimensional array

Geoframer geoframer at gmail.com
Tue Mar 13 11:57:14 CET 2007

```Hey everyone,

I've been trying to locate a way to find the location of the minimum value
in an n*n array.
For instance suppose we have a 10x10 array.

In [1]: import numpy
In [2]: a = numpy.zeros((10,10))
In [3]: a
Out[3]:
array([[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.]])

And we set a value in that array to be the smallest just for illustration
purposes.

In [4]: a[9][8] = -1
In [5]: a
Out[5]:
array([[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0., -1.,  0.]])

I can find this minimum using the 'min' function, but is there a way to find
the index to that position?

In [6]: a.min()
Out[6]: -1.0

Any help is appreciated. Please keep in mind that this is only a 'small'
example. What i'm trying to accomplish is to find the location of the
minimum value in a huge n*n array and quickly and efficiently finding the
index to that position.

Regards - Geofram
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