Check for dict key existence, and modify it in one step.

[Evan Klitzke]

On Tue, 2007-08-28 at 14:36 +0000, rodrigo wrote:
> Im using this construct a lot:
> 
> if dict.has_key(whatever):
>     dict[whatever] += delta
> else:
>     dict[whatever] = 1

In Python 2.5 there's a defaultdict class, otherwise you can subclass
dict like this:

class CountingDictionary(dict):
    def increment(self, key, delta=1):
        self[key] = self.get(key, 0) + delta

Hope this helps!

-- 
Evan Klitzke <evan at yelp.com>