trictionary?

[Steven Bethard]

Randy Bush wrote:
> now i want to add a second count column, kinda like
> 
>     bin = {}
>     for whatever:
>        for [a, b] in foo:
> 	  x = 42 - a
> 	  if bin.has_key(x):
> 	     bin[x.b] += 1
> 	  else:
> 	     bin[x.b] = 1
> 	     bin[x.not b] = 0
>     for x, y, z in bin.iteritems():
>        print x, y, z
> 
> should the dict value become a two element list, or is
> there a cleaner way to do this?

It would probably help if you explained what the real problem is you're 
trying to solve.  Using a two element list to store a pair of counts has 
a bad code smell to me.

That said, you could write your code something like:

     bin = {}
     for whatever:
        # NOTE: brackets are unnecessary
        for a, b in foo:
	  x = 42 - a
           # NOTE: 'in' is generally faster than has_key()
	  if x in bin
	     bin[x][0] += 1
	  else:
              bin[x] = [1, 0]
     # NOTE: extra parens necessary to unpack count list
     for x, (y, z) in bin.iteritems():
        print x, y, z

STeVe