C# 数据表按计数和不同分组

Question

I have a datatable that looks like the one in the picture.

With the below code I'm trying to count how many units each client id has in the each project. My problem is I can't seem to exclude the duplicate units.

var projectsGroup = dt.AsEnumerable().GroupBy(g => g.Field<string>("Project"));
foreach (var projectGroup in projectsGroup)
{
    var clientGroups = dt.AsEnumerable().GroupBy(g => g.Field<string>("ClientId"));
    foreach (var clientGroup in clientGroups)
    {
        var test = dt.AsEnumerable()
            .Where(r => r.Field<string>("ClientId") == clientGroup.Key && r.Field<string>("Project") == projectGroup.Key)
            .Select(r => r.Field<string>("Project"));

        //   Console.WriteLine(test.FirstOrDefault() + " " + test.Count());
    }
}

So my question is, how can I exclude these from being counted?

Answer 1

Try something like this:

var projectsGroups = dt.AsEnumerable()
                       .GroupBy(r => r.Field<string>("Project"))
                       .Select(pg => new {
                           Project = pg.Key,
                           Clients = pg.GroupBy(r => r.Field<string>("ClientId"))
                                       .Select(cg => new {
                                           ClientId = cg.Key,
                                           UnitCount = cg.Select(r => r.Field<string>("Unit"))
                                                          .Distinct()
                                                          .Count()
                                       })
                       })
                       .ToList();

foreach (var pg in projectsGroups) {
    foreach (var client in pg.Clients) {
        Console.WriteLine($"In Project {pg.Project}, Client {client.ClientId} has {client.UnitCount} unit{(client.UnitCount == 1 ? "" : "s")}");
    }
}