Question

我有几个袋子，每个袋子装满了多个苹果容器，每个容器可能有0个或更多的苹果。

public class Bag
{
    public List<Container> Containers { get; set; }
}

public class Container
{
    public List<Apple> Apples { get; set; }
}

public class Apple
{
    public double Weight { get; set; }
}

如果我有一个集合List<Bag> bags，如何在C＃中通过Linq计算所有苹果的总重量？

Answer 1

var bags = ...;

var total = bags.Sum(b => b.containers.Sum(c => c.apples.Sum(a => a.weight)) );

编辑：按要求添加说明（尽管代码本身就是解释性的，解释是多余的）：

阅读从最里面到外面的代码，我们正在总结苹果＆＃39;每个容器的重量，然后是容器＆＃39;总和，然后最后袋子＆＃39;总计：它看起来像这样：

Bag1
 +-----Container1
 |        +------Apple   10
 |        +------Apple   20
 |----------------------------------
 |      Container Total  30
 +-----Container2
 |         +------Apple   11
 |         +------Apple   22
 |         +------Apple   33
 |----------------------------------
 |      Container Total   66
 |----------------------------------
 | Bag Total              96
... Other bags
 |----------------------------------
    Grand total           ...

Answer 2

List<Bag> bags = ...
List<Container> containers = bags.SelectMany(bag => bag.Containers);
List<Apple> apples = containers.SelectMany(container => container.Apples);
var totalWeight = apples.Sum(apple => apple.Weight);

SelectMany扩展方法用于在执行总和之前将二维数据结构展平为一维结构

Answer 3

试试这个

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Bag> bags = new List<Bag>() {
                new Bag() { containers = new List<Container>() {
                    new Container() { apples = new List<Apple>() {
                        new Apple() { weight = 1.0},
                        new Apple() { weight = 1.2},
                        new Apple() { weight = 1.3}
                    }},
                    new Container() { apples = new List<Apple>() {
                        new Apple() { weight = 0.9},
                        new Apple() { weight = 1.15}
                    }}
                }},
                new Bag() { containers = new List<Container>() {
                    new Container() { apples = new List<Apple>() {
                        new Apple() { weight = 1.0},
                        new Apple() { weight = 1.2},
                        new Apple() { weight = 1.3}
                    }},
                    new Container() { apples = new List<Apple>() {
                        new Apple() { weight = 0.9},
                        new Apple() { weight = 1.15}
                    }}
                }}
            };

            double total = bags.Select(x => x.containers.Select(y => y.apples.Select(z => z.weight))).SelectMany(a => a).SelectMany(b => b).Sum();
        }
    }
    public class Bag
    {
        public List<Container> containers { get; set; }
    }
    public class Container
    {
        public List<Apple> apples { get; set; }
    }
    public class Apple
    {
        public double weight { get; set; }
    }

}

使用Linq选择总和

3 个答案: