Comparing a matrix (list[][]) ?

[bearophileHUGS at lycos.com]

Roberto Bonvallet:
> What output are you expecting from your example matrix?  If you are expecting
> it to be 5 (the smallest positive element), using "min" is the way to do it:
>     >>> matrix = [[9,  8, 12, 15],
>     ...           [0, 11, 15, 18],
>     ...           [0,  0, 10, 13],
>     ...           [0,  0,  0,  5]]
>     >>> min(min(x for x in row if x > 0) for row in matrix)
>     5

This looks a bit like homework...
To find the minimal number > 0 of the matrix this seems better:

mat = [[9, 8,  12, 15],
       [0, 11, 15, 18],
       [0,  0, 10, 13],
       [0,  0,  0,  5]]

print min(el for row in mat for el in row if el > 0)

Note that this raises TypeError is the matrix doesn't have one or more
numbers > 0
If the OP needs the position he/she can do something like:

nozeromin = 1e300 # or something similar
pos = None, None

for nrow, row in enumerate(mat):
    for ncol, el in enumerate(row):
        if el > 0 and el < nozeromin:
            nozeromin = el
            pos = nrow, ncol

print nozeromin, pos

Bye,
bearophile