[Tutor] array

[Danny Yoo]

On Sun, 17 Mar 2002, Paul Sidorsky wrote:

> Karshi wrote:
> 
> >  How do find the maximum number in an array: say A[i,j] ?
> > I've got the following error when I tried to use "max":
> > --------------------------------------------------------------------
> > >>> M=array([[1,2,3,],[3,4,56],[4,6,8]], Float32)
> > >>> M
> > array([[  1.,   2.,   3.],
> >        [  3.,   4.,  56.],
> >        [  4.,   6.,   8.]],'f')
> > >>> max(M)
> > array([ 4.,  6.,  8.],'f')
> > ---------------------------------------------------------------------
> > which is not true.

Numeric's 'Ufuncs' work on entire columns at a time, so you may need to
apply the max() Ufunc twice to get the effect you want:


###
>>> from Numeric import *
>>> M = array([[1, 2, 3],
...            [4, 5, 6],
...            [7, 8, 9]])
>>> 
>>> M
array([[1, 2, 3],
       [4, 5, 6],
       [7, 8, 9]])
>>> max(M)
array([7, 8, 9])
>>> max(max(M))
9
###


You can read more details about Ufuncs here:

    http://www.pfdubois.com/numpy/html2/numpy-7.html#pgfId-36126

Good luck!