Subj : Re: any function to handle this kind of counting?
To   : comp.programming
From : mensanator@aol.com
Date : Fri Jul 29 2005 11:58 am


Ross wrote:
> Dear all,
>
> i have generated a 2000 X 1 vector, e.g.
>
>
> 1
> 3
> 2
> 1
> 1
> 3
> 2
> 1
> 1
> 4
> ...
>
> and this vector indeed has a corresponding vector, e.g.
>
> A
> A
> A
> A
> C
> C
> E
> E
> ...
>
> and then i want to count, say, for "1", there are two A's, one E, ...
>
> it seems that a for loop can do the job but as we don't know how many
> instances there are, i.e. don't know A, C, E and then what will occur in
> this corresponding vector, is there any function which is devoted to handle
> this kind of counting problem? thx!!

Something like this, perhaps?

>>> v = [1,3,2,1,1,3,2,1,1,4]
>>> w = ['A','A','A','A','C','C','E','E','B','B']
>>> h = {}
>>> for i in range(len(v)):
	if h.has_key((v[i],w[i])):
		h[(v[i],w[i])] += 1
	else:
		h[(v[i],w[i])] = 1


>>> for k in h.items():
	print k


((3, 'C'), 1)
((3, 'A'), 1)
((4, 'B'), 1)
((2, 'E'), 1)
((1, 'A'), 2)
((1, 'B'), 1)
((1, 'C'), 1)
((2, 'A'), 1)
((1, 'E'), 1)

.