计算平均值并平均拆分列表不起作用

Question

我有一张叫做汽车的物品清单。每辆车都是一个元组，第一个元素是一个数字。我在所有汽车中找到这个数字的平均值，然后尝试将它们在中点上分成两半，使用分治算法。然而，所有的车都驶入左侧，没有一辆驶入右侧

    l = sum(car[1] for car in car)/2

    # all cars go in to this side 
    leftBeds = [car for car in cars if car[1] <= l]

    # no cars go into this side
    rightBeds = [car for car in cars if car[1] > l]

Answer 1

您需要将所有车辆数量之和除以车辆数量——而不是除以2

cars = [("car 1" ,1), ("car 2",2), ("car 3",3), ("car 4",4), ("car 5",5)]

l = sum(car[1] for car in cars)/len(cars)

# all cars go in to this side 
leftBeds = [car for car in cars if car[1] <= l]

# no cars go into this side
rightBeds = [car for car in cars if car[1] > l]

print(l)
print(leftBeds,rightBeds)  

输出：

3.0
[('car 1', 1), ('car 2', 2), ('car 3', 3)] [('car 4', 4), ('car 5', 5)]

---

如果你想要一个中点，为什么不简单点呢

lc = len(cars)
c1,c2 = cars[:lc//2], cars[lc//2:]

Answer 2

首先，检查代码的第一行：

l = sum(car[1] for car in car)/2

它应该看起来像：

l = sum(car[1] for car in cars)/len(cars)

两件事：“车中有车”；如果你想要平均值，你应该用sum（）除以汽车的数量

此外，任何序列（包括元组）的第一个元素的索引为[0]。如果要使用每个元组中的实际第一个元素，请将[1]替换为[0]