Adjacency matrix in Python

Question

I cannot find any clear explanation as to how to create an adjacency matrix in Python, with weights taken into consideration. I assume it should be relatively simple to create.<

Answer 1

I like tupled keys for 2d structures like this in python.

{(1, 1): 0, (3, 2): 9... }

I think it's conceptually clearest since it drops the intermediary data structure in the above solution. Nonetheless, that intermediary data structure -- the inner list or row / column-- can be useful if you intend to access your structure either row or column wise.

 for x, row in enumerated(matrix, 1):
       # process whole row 
       for y in enumerate(row, 1):
             # process cell...

If cell-wise data access is your game though, it's hard to beat the following for expressive simplicity:

for (x, y), value in matrix.iteritems():
      # act on cell

Sort it if you want.

 # (1, 1), (1, 2)...
 for (x, y), value in sorted(matrix.iteritems()):
       # act on cell