c# - 如何将这段代码重写为LINQ？

Question

我有以下非常丑陋的代码，我想用一些不错的LINQ重写它，但我无法弄清楚：

var folders = new List<string>();
string folderResult = "";

foreach (var parallelMeasurement in ParallelMeasurements)
{
    var folder = parallelMeasurement.Item1.Substring(0, parallelMeasurement.Item1.IndexOf("."));

    if (!folders.Contains(folder))
    {
        folders.Add(folder);
        folderResult += folder + ",";
    }
}

folderResult = folderResult.TrimEnd(',');

string valueResult = "";

foreach (var folder in folders)
{
    var views = ParallelMeasurements.Where(x => x.Item1.Substring(0, x.Item1.IndexOf(".")) == folder);

    var value = views.Sum(x => x.Item2.TotalSeconds);
    valueResult += value + ",";
}

valueResult = valueResult.TrimEnd(',');

File.WriteAllText(Paths.ParallelGroupedTrend, $"{folderResult}{Environment.NewLine}{valueResult}");

ParallelMeasurements是List<Tuple<string, TimeSpan>>，元组的内容例如是：

Actor.ActorUsers
Actor.ActorInformation
User.Edit

简而言之，我想基于字符串的第一部分，即句点之前的内容，汇总度量。

Answer 1

这应该怎么办？

ParallelMeasurements.Add(new Tuple<string, TimeSpan>("Actor.ActorUsers", TimeSpan.FromMilliseconds(150)));
ParallelMeasurements.Add(new Tuple<string, TimeSpan>("Actor.ActorInformation", TimeSpan.FromMilliseconds(200)));
ParallelMeasurements.Add(new Tuple<string, TimeSpan>("User.Edit", TimeSpan.FromMilliseconds(150)));

var folders =
    ParallelMeasurements
        .GroupBy(g => g.Item1.Substring(0, g.Item1.IndexOf(".", StringComparison.InvariantCulture)))
        .Select(s => new { Group = s.Key, Sum = s.Sum(a => a.Item2.Milliseconds) })
        .ToList();

var folderResult = string.Join(",", folders.Select(f => f.Group));
var valueResult = string.Join(",", folders.Select(f => f.Sum));

Console.WriteLine("{0}{1}{2}", folderResult, Environment.NewLine, valueResult);

打印输出

Actor,User
350,150