Hi, 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?
Example::
In [7]: metrics = {'f':6, 'g':1}
In [8]: avg_metrics = ['f']
In [9]: a = CounterExt(avg_metrics=avg_metrics)
In [10]: a.update(metrics)
In [11]: a
Out[11]: CounterExt({'f': 6, 'g': 1})
In [12]: a.update(metrics)
In [13]: a
Out[13]: CounterExt({'f': 12, 'g': 2})
In [14]: a['f']
.........
RuntimeError: maximum recursion depth exceeded
Code::
from collections import Counter
from collections.abc import Mapping
class CounterExt(Counter):
def __init__(self, iterable=None, avg_metrics=None, **kwds):
self._counter = 1 # a zero value will raise ZeroDivisionError
self.avg_metrics = avg_metrics
super().__init__()
self.update(iterable, **kwds)
def _count_elements(self, iterable):
"""Tally elements from the iterable.
This is copied from collections/__init__.py
original code::
def _count_elements(mapping, iterable):
'Tally elements from the iterable.'
mapping_get = mapping.get
for elem in iterable:
mapping[elem] = mapping_get(elem, 0) + 1
"""
for elem in iterable:
self[elem] = self.get(elem, 0) + 1
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]
def update(self, iterable=None, **kwds):
if iterable is not None:
if isinstance(iterable, Mapping):
if self:
self_get = self.get
self._counter +=1 # local modification
for elem, count in iterable.items():
self[elem] = count + self_get(elem, 0)
else:
super().update(iterable)
else:
self._count_elements(iterable)
if kwds:
self.update(kwds)
signature.asc
Description: OpenPGP digital signature
-- https://mail.python.org/mailman/listinfo/python-list
