python - 如何找到计数器的第二个最大值 - Python

Question

计数器的最大值可以这样访问:

c = Counter()
c['foo'] = 124123
c['bar'] = 43
c['foofro'] =5676
c['barbar'] = 234
# This only prints the max key
print max(c), src_sense[max(c)] 
# print the max key of the value
x = max(src_sense.iteritems(), key=operator.itemgetter(1))[0]
print x, src_sense[x]

如果我想要一个按降序计数的排序计数器怎么办？

我如何访问第 2 个最大值、第 3 个或第 N 个最大值 key ？

Answer 1

most_common(self, n=None) method of collections.Counter instance

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('abcdeabcdabcaba').most_common(3)
[('a', 5), ('b', 4), ('c', 3)]

等等:

>>> c.most_common()
[('foo', 124123), ('foofro', 5676), ('barbar', 234), ('bar', 43)]
>>> c.most_common(2)[-1]
('foofro', 5676)

请注意 max(c) 可能不会返回您想要的内容:Counter 上的迭代是键上的迭代，因此 max(c ) == max(c.keys()) == 'foofro'，因为它是字符串排序后的最后一个。你需要做类似的事情

>>> max(c, key=c.get)
'foo'

获取具有最大值的 (a) 键。以类似的方式，您可以完全放弃 most_common 并自己进行排序:

>>> sorted(c, key=c.get)[-2]
'foofro'