以降序遍历 collections.Counter() 实例的 Pythonic 方式?
问题描述
在 Python 2.7 中，我想以递减计数顺序迭代 collections.Counter 实例.
In Python 2.7, I want to iterate over a collections.Counter instance in descending count order.
>>> import collections
>>> c = collections.Counter()
>>> c['a'] = 1
>>> c['b'] = 999
>>> c
Counter({'b': 999, 'a': 1})
>>> for x in c:
print x
a
b
在上面的示例中，元素似乎按照它们添加到 Counter 实例的顺序进行迭代.
In the example above, it appears that the elements are iterated in the order they were added to the Counter instance.
我想从最高到最低遍历列表.我看到 Counter 的字符串表示是这样做的，只是想知道是否有推荐的方法.
I'd like to iterate over the list from highest to lowest. I see that the string representation of Counter does this, just wondering if there's a recommended way to do it.
解决方案
您可以遍历 c.most_common() 以按所需顺序获取项目.另请参阅 Counter.most_common() 的文档.
You can iterate over c.most_common() to get the items in the desired order. See also the documentation of Counter.most_common().
例子:
>>> c = collections.Counter(a=1, b=999)
>>> c.most_common()
[('b', 999), ('a', 1)]
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