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Backport r87672 and r87615, improving tests, using super() instead of direct parent references, and using __reduce__ method for pickling.

This commit is contained in:
Raymond Hettinger 2011-01-03 08:50:48 +00:00
parent 32e8aab1fb
commit 8dfb9288af
1 changed files with 15 additions and 11 deletions
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26
Lib/collections.py
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@ -298,16 +298,16 @@ class Counter(dict):
or multiset. Elements are stored as dictionary keys and their counts
are stored as dictionary values.
>>> c = Counter('abracadabra') # count elements from a string
>>> c = Counter('abcdeabcdabcaba') # count elements from a string
>>> c.most_common(3) # three most common elements
[('a', 5), ('r', 2), ('b', 2)]
[('a', 5), ('b', 4), ('c', 3)]
>>> sorted(c) # list all unique elements
['a', 'b', 'c', 'd', 'r']
['a', 'b', 'c', 'd', 'e']
>>> ''.join(sorted(c.elements())) # list elements with repetitions
'aaaaabbcdrr'
'aaaaabbbbcccdde'
>>> sum(c.values()) # total of all counts
11
15
>>> c['a'] # count of letter 'a'
5
@ -315,8 +315,8 @@ class Counter(dict):
... c[elem] += 1 # by adding 1 to each element's count
>>> c['a'] # now there are seven 'a'
7
>>> del c['r'] # remove all 'r'
>>> c['r'] # now there are zero 'r'
>>> del c['b'] # remove all 'b'
>>> c['b'] # now there are zero 'b'
0
>>> d = Counter('simsalabim') # make another counter
@ -355,6 +355,7 @@ class Counter(dict):
>>> c = Counter(a=4, b=2) # a new counter from keyword args
'''
super().__init__()
self.update(iterable, **kwds)
def __missing__(self, key):
@ -366,8 +367,8 @@ class Counter(dict):
'''List the n most common elements and their counts from the most
common to the least. If n is None, then list all element counts.
>>> Counter('abracadabra').most_common(3)
[('a', 5), ('r', 2), ('b', 2)]
>>> Counter('abcdeabcdabcaba').most_common(3)
[('a', 5), ('b', 4), ('c', 3)]
'''
# Emulate Bag.sortedByCount from Smalltalk
@ -433,7 +434,7 @@ class Counter(dict):
for elem, count in iterable.items():
self[elem] = count + self_get(elem, 0)
else:
dict.update(self, iterable) # fast path when counter is empty
super().update(iterable) # fast path when counter is empty
else:
self_get = self.get
for elem in iterable:
@ -445,10 +446,13 @@ class Counter(dict):
'Like dict.copy() but returns a Counter instance instead of a dict.'
return Counter(self)
def __reduce__(self):
return self.__class__, (dict(self),)
def __delitem__(self, elem):
'Like dict.__delitem__() but does not raise KeyError for missing values.'
if elem in self:
dict.__delitem__(self, elem)
super().__delitem__(elem)
def __repr__(self):
if not self: