Hi guys,
I've got a problem with my program, in that the code just takes too
long to run. Here's what I'm doing. If anyone has any tips, they'd be
much appreciated!
So, say I have a list of lists that looks something like this (I'm
using a list of lists, rather than a list of tuples, as I need it to
be mutable):
myList = [[786,0],[45, 1],[673,1],...................[23,46]]
there are enough entries in the outer list, that the sum of myList[i]
[0] across all i could be as high as 10^7.
Now, what I need to do is randomly choose one myList[i], however the
distribution of my random choice needs to be proportional to the
values of myList[i][0]. So, for this list above, I'd have a much
higher chance of choosing myList[0] than myList[1].
Here is how I'm doing it at the moment:
def chooseI(myList):
mySum=0
choice = random.choice(range(1,sum([i[0] for i in myList])+1))
for i in range(len(myList)):
mySum+=myList[i][0]
if mySum>=choice:
return i
break
This works just fine if sum([i[0] for i in myList]) is less than
10,000, say. However if its up around 10^7, the whole thing crashes.
Is there a faster way of doing this, that doesn't involve as many
computational steps?
Thanks!
elsa
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