python - 如何通过一次循环对多个对象属性求和(求和)？

Question

我想在一个循环中一次对多个属性求和:

class Some(object):
    def __init__(self, acounter, bcounter):
        self.acounter = acounter
        self.bcounter = bcounter

someList = [Some(x, x) for x in range(10)]

我可以做一些比它更简单、更快的事情吗？

atotal = sum([x.acounter for x in someList])
btotal = sum([x.bcounter for x in someList])

Answer 1

首先 - sum 不需要列表 - 你可以使用生成器表达式来代替:

atotal = sum(x.acounter for x in someList)

您可以编写一个辅助函数来搜索列表一次，然后按项目依次查找每个属性，例如:

def multisum(iterable, *attributes, **kwargs):
    sums = dict.fromkeys(attributes, kwargs.get('start', 0))
    for it in iterable:
        for attr in attributes:
            sums[attr] += getattr(it, attr)
    return sums

counts = multisum(someList, 'acounter', 'bcounter')
# {'bcounter': 45, 'acounter': 45}