Improving style (and speed)?

[ingo]

Dear all,
A week or two ago I started learning programming and Python. Did a few small 
things so far and they work :) Trying something bigger now; manipulating a 
3D-dataset. There's one part in it, although it works, I don't like the way 
I did it. But I can't find a better, more elegant, way to do it. Lack of 
experience. So I'm looking for some guidance.

What I'm doing is select a small (3x3) region in the dataset. Within this 
selection find the minimum value and its indices in the 3d-dataset . If 
there are more minima select one randomly. I'm not yet taking into account 
that the selection also can be 2x2, 2x3 or 3x2 when it's on one of te edges 
of the dataset.

Coming from "Array3d[Posx, Posy, Posz]"

Miny=Posy-1
if Miny<0:
    Miny=0
Maxy=Posy+2
Minz=Posz-1
if Minz<0:
    Minz=0
Maxz=Posz+2

Nine=Numeric.ravel(Array3d[Posx, Miny:Maxy, Minz:Maxz])
MinNine=min(Nine)
EqMin=Numeric.equal(Nine,MinNine)
MinIndex=Numeric.nonzero(EqMin)
Index=whrandom.randint(0,len(MinIndice)-1)
MinIndex=MinIndex[Index]

if MinIndex==0:
    Posy=Posy-1
    Posz=Posz-1
elif MinIndex==1:
    Posy=Posy
    Posz=Posz-1
elif MinIndex==2:
    Posy=Posy+1
    Posz=Posz-1
elif MinIndex==3:
    Posy=Posy-1
    Posz=Posz
elif MinIndex==4:
    Posy=Posy
    Posz=Posz
elif MinIndex==5:
    Posy=Posy+1
    Posz=Posz
elif MinIndex==6:
    Posy=Posy+1
    Posz=Posz-1
elif MinIndex==7:
    Posy=Posy+1
    Posz=Posz
elif MinIndex==8:
    Posy=Posy+1
    Posz=Posz+1

now do something with "Array3d[Posx, Posy, Posz]"

TIA,
Ingo

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