c# - 将字符串拆分为字典作为键，列表

Question

我有一个字符串类型，它将以格式返回数千条记录

key1,val1,val2,val3,val4,val5:key2,val6,val7,val8,val9,val10:key3,val11,val12,val13,val14,val15

我想把它作为 Key,List 分配给一个字典，这样它看起来像

key1,[val1,val2,val3,val4,val5]

key2,[val6,val7,val8,val9,val10]

key3,[val11,val12,val13,val14,val15]

...

所有键在字符串中都是唯一的，并且列表大小对于所有记录都是恒定的。

目前我正在使用 Split 并使用循环每条记录

    //short example string - may contain 1000's
    string newstr = @"key1,val1,val2,val3,val4,val5:key2,val6,val7,val8,val9,val10:key3,val11,val12,val13,val14,val15";

    Dictionary<string, List<string>> mydictionary = new Dictionary<string, List<string>>();
    foreach (string item in newstr.Split(':'))
    {
        List<string> list = new List<string>(item.Split(','));
        mydictionary.Add(list[0], list);        
    }

我的问题是，对于使用 C#4.0 的 1000 条记录，是否有一种比循环更有效/更快速的方法？

更新:测试了各种答案后，以下是“正确”时间

static void Main(string[] args)
{
    System.IO.StreamReader myFile =  new System.IO.StreamReader(@"C:\Users\ooo\Desktop\temp.txt");
    string newstr = myFile.ReadToEnd();
    myFile.Close();

    TimeSpan ts;
    TimeSpan te;
    Stopwatch stopWatch = new Stopwatch();
    stopWatch.Start();


    ts = stopWatch.Elapsed;
    Dictionary<string, List<string>> mydictionary = new Dictionary<string, List<string>>();
    foreach (string item in newstr.Split(':'))
    {
        List<string> list = new List<string>(item.Split(','));
        mydictionary.Add(list[0], list);
    }
    te = stopWatch.Elapsed;
    Console.WriteLine("MyTime: " + (te - ts).ToString());



    ts = stopWatch.Elapsed;
    var result = newstr.Split(':')
         .Select(line => line.Split(','))
         .ToDictionary(bits => bits[0],
                       bits => bits.Skip(1).ToList());
    te = stopWatch.Elapsed;
    Console.WriteLine("JonSkeet: " + (te - ts).ToString());


    ts = stopWatch.Elapsed;
    string[] keysAndValues = newstr.Split(':');
    var newdictionary = new Dictionary<string, List<string>>(keysAndValues.Length);
    foreach (string item in keysAndValues)
    {
        List<string> list = new List<string>(item.Split(','));
        newdictionary.Add(list[0], list);
    }
    te = stopWatch.Elapsed;
    Console.WriteLine("Joe: " + (te - ts).ToString());


    Console.WriteLine("Records: " + mydictionary.Count.ToString());


    stopWatch.Stop();
}

Answer 1

以下可能更快，因为字典的构建具有避免重新分配所需的容量:

//short example string - may contain 1000's     
string newstr = ...;

string[] keysAndValues = newstr.Split(':');
var mydictionary = new Dictionary<string, List<string>>(keysAndValues.Length);
foreach (string item in keysAndValues)     
{         
    List<string> list = new List<string>(item.Split(','));         
    mydictionary.Add(list[0], list);
    // remove key from list to match Jon Skeet's implementation
    list.RemoveAt(0);
} 

虽然可读性不如 Jon Skeet 的 LINQ 版本。