我有一个计数器的字典,例如:
from collections import Counter, defaultdict
numbers = defaultdict(Counter)
numbers['a']['first'] = 1
numbers['a']['second'] = 2
numbers['b']['first'] = 3
我想要得到一个加和:1+2+3 = 6
在Python 3中,最简单/惯用的方法是什么?
我有一个计数器的字典,例如:
from collections import Counter, defaultdict
numbers = defaultdict(Counter)
numbers['a']['first'] = 1
numbers['a']['second'] = 2
numbers['b']['first'] = 3
我想要得到一个加和:1+2+3 = 6
在Python 3中,最简单/惯用的方法是什么?
使用嵌套推导式:
sum(x for counter in numbers.values() for x in counter.values())
首先创建一个空计数器,然后求和它们的值:
sum(sum(numbers.values(), Counter()).values())
sum(sum(c.values()) for c in numbers.values())
from itertools import chain
sum(chain.from_iterable(d.values() for d in numbers.values()))
sum(sum(c.values()) for c in numbers.values())
from itertools import chain
sum(chain.from_iterable(d.values() for d in numbers.values()))
# outputs: 6
.itervalues()
,这可以避免构建中间列表(适用于此处的所有解决方案)。sum(chain.from_iterable(d.itervalues() for d in numbers.itervalues()))