How to access elemenst in a list of lists?

[Algis Kabaila]

On Tuesday 10 May 2011 05:24:16 Terry Reedy wrote:
> On 5/9/2011 4:25 AM, Antonio CHESSA wrote:
> > apple =
> > [["a","b","c"],[1,2,3,4,5,6],["antony","max","sandra","seb
> > astian"]]
> >    for j in range (len(apple[i])):
> >       print apple[i][j]
> 
> While this illustrate double indexing, it can be simplified
> to
> 
> for top in apple:
>    print(top)
>    for inner in top:
>       print(inner)
> 
> and give the same output. Indexing is only needed for random
> access and for changing a list in place.

The method of double indexing in the manner
apple[i][j]
or
a[i][j]
for the (i, j) -th element of multi-dimensional array is well 
known and widely used.  But how to enable the "standard" matrix 
notation
a[i, j]
in Python 3.2 in the manner of numpy (and other matrix 
packages)?  Is it  subclassing of "special methods"

__getitem__()
 
and/or  

__setitem__()

and if so how?


OldAl.
-- 
Algis
http://akabaila.pcug.org.au/StructuralAnalysis.pdf
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