subclassing collections.Counter
Peter Otten
__peter__ at web.de
Tue Dec 15 11:08:15 EST 2015
Pavlos Parissis wrote:
> I need to store values for metrics and return the average for some
> and the sum for the rest. Thus, I thought I could extend
> collections.Counter class by returning averages for some keys.
>
> My class modifies the update() to increment a counter and the
> __getitem__ to perform the calculation. But, I get RuntimeError: maximum
> recursion depth exceeded as I access an attribute inside
> __getitem__.
>
> Does anyone has an idea how I can achieve this?
> class CounterExt(Counter):
> def __getitem__(self, key):
> if (self.avg_metrics is not None and key in self.avg_metrics):
> return self[key] / self._counter
> else:
> return self[key]
self[key] will call the CounterExt.__getitem__() method again. Use
super().__getitem__(key) instead to invoke Counter.__getitem__().
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