排序2维列表基于第一indexvalue [英] Sort 2 dimensional List based on first indexvalue

问题描述

我在添加以下值到我的2D名单（名单列表）。它包含重量水果其次是他们的名字。你能告诉我如何排序权重的第一指标值这个二维数组基地？

I have added following values in to my 2D List (List of Lists). It contains weight of fruits followed by their names. Can you please tell me how can I sort this 2D array base on the first index value of weight?

List<List<String>> matrix = new List<List<String>>();
matrix.Add(new List<String>()); //Adds new sub List
matrix[0].Add("3.256"); 
matrix[0].Add("Apple");       

matrix.Add(new List<String>());
matrix[1].Add("1.236"); 
matrix[1].Add("Orange");           

matrix.Add(new List<String>());
matrix[2].Add("1.238"); 
matrix[2].Add("Banana");

matrix.Add(new List<String>());
matrix[2].Add("2.658"); //updated This should be matrix[3] instead of 2
matrix[2].Add("Apple");
....
...
..

Console.WriteLine(matrix[0][0]);//This prints out the value 3.256. after sorting it should print out 1.236

我是新的C＃和请给我一个例子，如果这是可能的。

I am new to C# and please show me with an example if this is possible

推荐答案

答案很简单：

matrix.OrderBy( l => l[0]);

好吧，这是一个的真正的设计不好，一是因为该字符串比较是的不的要给你一个双击比较会。易不足以解决：

Okay, this is a really bad design, first because the string compare is not going to give you the same order a double compare would. Easy enough to fix:

matrix.OrderBy( l => double.Parse(l[0]));

除了现在它会抛出一个异常，如果你错误地输入一个数字（并且不能被解析成一个双）。您的真正的想要做的是创造一个果的对象：

Except now it will throw an exception if you typed a number incorrectly (and can't be parsed into a double). What you really want to do is create a "Fruit" object:

class Fruit
{
    public string Name { get; set; }
    public double Weight { get; set; }
}

和持有列表与LT;水果GT; 。现在，你可以写：

And hold a List<Fruit>. Now you can write:

matrix.OrderBy(f => f.Weight);

使用有例外没有问题，因为如果你写，你会得到一个编译时错误是错误的。

With no problems with exceptions, since you will get a compile time error if you wrote it wrong.

的OrderBy返回一个IEnumerable，所以一定要确保在打印时使用的返回值，而不是矩阵

OrderBy returns an IEnumerable, so make sure you utilize the return value instead of matrix when printing

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