基于查找表为数组元素赋值

Question

我正在编写一个C#程序，在这个程序中，我需要使用元数据填充一个基于查找表和一组字符串数组的数组。我的查找表如下所示(带有键的表:发射器，值:接收器数组)：

{
    LED1: ["px1","px2","px3"],
    LED2: ["px4","px5","px6"]
}

我的元数组看起来像这样(它是动态的(只是一个例子)，并作为来自DB查询的响应)：

var transmitters = new string[] { "LED1", "LED2" };
var receivers = new string[] { "px1", "px2", "px3", "px4", "px5", "px6" };

我的要求是：

• 如果发射机LED1或LED2 (或任何其他发射机)存在于查找表中，则必须将发射机(即“px1”“px2”“px3”)的值与存在于查找和引导中的接收机进行比较。
• 孤儿发射机或/接收器必须标记为红色。

示例

查找

{
        LED1: ["px1", "px2", "px3"],
        LED2: ["px5", "px8"]
}

发射机和接收器

var transmitters = new string[] { "led1", "led2" };
var receivers = new string[] { "px1", "px2", "px3", "px4", "px5", "px6" };

结果应该是一份清单如下：

led1-yellow
px1-yellow
px2-yellow
px3-yellow
led2-yellow
px5-yellow
px4-red
px6-red.

我编写的代码可以：

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


public class Program
{
    public static void Main()
    {
      var transmitters = new string[] { "led1", "led2", "led3" };
      var receivers = new string[] { "px1", "px2", "px3", "px4", "px5", "px6" };
      var lookup = new Dictionary<string, string[]>() {
          { "led1", new string[] { "px1", "px2", "px3" } },
          { "led2", new string[] { "px5", "px8"} }
      };

      var blocks = new List<Block>();
      var blocksTracker = new List<string>();

      foreach (var transmitter in transmitters)
      {
        if (lookup.ContainsKey(transmitter))
        {
          var receiverLookup = lookup[transmitter];
          var intersection = receivers.Intersect(receiverLookup).ToArray();
          if (intersection.Length > 0)
          {
             blocks.Add(new Block() { Id = transmitter, status = "yellow"});
             blocksTracker.Add(transmitter);
            foreach (var receiver in intersection)
            {
              blocks.Add(new Block(){Id = receiver, status = "yellow"});
              blocksTracker.Add(receiver);
            }
          } else  
          {
            blocks.Add(new Block(){Id = transmitter, status = "red"});
            blocksTracker.Add(transmitter);   
          }
        }
      }

      var ungrouped = receivers.Except(blocksTracker).ToArray();

      foreach (var receiver in ungrouped)
      {
        blocks.Add(new Block(){Id = receiver, status = "red"});
        blocksTracker.Add(receiver);
      }

      foreach (var i in blocks)
      {
        Console.WriteLine(i.Id + "-"+i.status);
      }
    }

    public class Block
    {
      public string Id { get; set; }

      public string status { get; set; }
    }
}

我是C#的新手，我想知道是否有更好的方法来做到这一点。您可以看到工作Fiddle 这里。

Answer 1

if (lookup.ContainsKey(transmitter)) { var receiverLookup = lookup[transmitter];

这将搜索两次KeyValuePair。有一种更有效的方法：

        if (lookup.TryGetValue(transmitter, out var receiverLookup))

var ungrouped = receivers.Except(blocksTracker).ToArray(); foreach (var receiver in ungrouped) { blocks.Add(new Block(){Id = receiver, status = "red"}); blocksTracker.Add(receiver); }

这里的ToArray()是不必要的:枚举可以保留为惰性枚举，因为惟一的用途是对它进行一次迭代。

var intersection = receivers.Intersect(receiverLookup).ToArray(); if (intersection.Length > 0) { blocks.Add(new Block() { Id = transmitter, status = "yellow"}); blocksTracker.Add(transmitter); foreach (var receiver in intersection) { blocks.Add(new Block(){Id = receiver, status = "yellow"}); blocksTracker.Add(receiver); } } else { blocks.Add(new Block(){Id = transmitter, status = "red"}); blocksTracker.Add(transmitter); }

这似乎相当复杂。我认为整件事可以简化：

var transmittersPaired = new HashSet<string>();
var receiversPaired = new HashSet<string>();

foreach (var transmitter in transmitters)
{
    if (lookup.TryGetValue(transmitter, out var receiverLookup) && receiverLookup.Any())
    {
        transmittersPaired.Add(transmitter);
        foreach (var receiver in receiverLookup)
        {
            receiversSeen.Add(receiver);
        }
    }
}

var blocks = new List<Block>();
foreach (var transmitter in transmitters)
{
    blocks.Add(new Block { Id = transmitter, status = transmittersPaired.Contains(transmitter) ? "yellow" : "red" });
}
foreach (var receiver in receivers)
{
    blocks.Add(new Block { Id = receiver, status = receiversPaired.Contains(receiver) ? "yellow" : "red" });
}

还有一些重复的代码，这些代码可以通过两种方式中的一种进行简化。如果能够保证发射机和接收器永远不会共享If，那么transmittersPaired和receiversPaired就可以合并成一个集合，最后的foreach循环可以在transmitters.Concat(receivers)上合并成一个循环。或者，可以将一个方法考虑在内。