Brian van den Broek wrote:
2) To get around that, and be more efficient with matricies with many empty cells:
.>>> my_matrix_as_dict = {(1,1):4, (1,2):6, (1,3):8,
(2,1):56, (2,3):12,
(3,1):3, (3,2):3}
.>>> my_matrix_as_dict[(3,1)] 3 .>>> my_matrix_as_dict[(2,1)] 56
So, you just can use the tuple co-ordinates you've defined in order to access cells. Note also that the list way you'd have to represent empty cells with a standard null value -- None is the usual choice. But this way, you just don't define some tuples as keys, as I didn't define (2,2) as a key. Thus:
.>>> my_matrix_as_dict[(2,2)]
Traceback (most recent call last): File "<pyshell#19>", line 1, in -toplevel- my_matrix_as_dict[(2,2)] KeyError: (2, 2)
You can make that more graceful with a try/except block:
.>>> try:
my_matrix_as_dict[(2,2)]
except KeyError:
print "That cell is empty"
That cell is empty
.>>>
if you want None to be returned for an empty cell, you can just do:
my_matrix_as_dict.get((2,2), None)
so that the None object will de returned for all inexistant cells...
Hugo _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
