list comprehension

[Duncan Booth]

Patrick Maupin wrote:
>>>> def occurrences(t):
> ...     res = {}
> ...     for item in t:
> ...         res.setdefault(item,[0])[0] += 1
> ...     return res
> 
...
> I think somebody was mentioning "mutable ints" at one point,
> which is basically what I abuse [0] to provide.  If I were doing a lot
> of this in one place, I would code a mutable integer class, and then
> the rest of the code would get simpler.

Or you could use the facilities built in to Python: use the get method as 
Bryan did, and the code gets simpler without using mutable integers.

I prefer writing an 'if' statement here, Bryan prefers 'get', that's just a 
choice of style. But 'setdefault' here, that has no style.