Group linq results by value and group null or invalid values and do counts

问题

this is a follow on question to this question. I now would like to do some counts on the groupings.

Original Query: that excluded invalid zip codes did the following:

  List<DataSourceRecord> md = (from rst in QBModel.ResultsTable
        where (!String.IsNullOrWhiteSpace(rst.CallerZipCode) && rst.CallerZipCode.Length > 2)
        group rst by rst.CallerZipCode.Substring(0, 3) into newGroup
        orderby newGroup.Key
        select new DataSourceRecord()
        {
          State = newGroup.Select(i => i.CallerState).FirstOrDefault(),
          ZipCode = newGroup.Where(z => z.CallerZipCode.StartsWith(newGroup.Key)).Select(x => x.CallerZipCode.Substring(0, 3)).FirstOrDefault(),
          Calls = newGroup.Where(x => x.CallerZipCode.StartsWith(newGroup.Key) && x.CALL_ID > 0).Distinct().GroupBy(g => new { g.CallerZipCode, g.CTR_ID, g.CALL_ID }).Count(),
          Exposures = newGroup.Where(x => x.CallerZipCode.StartsWith(newGroup.Key) && x.CALL_ID > 0 && x.ExposureCount > 0).Distinct().GroupBy(x => new { x.CallerState, x.CTR_ID, x.CALL_ID }).Count()
        }).ToList();

New Example 1: Now with the new groupings including the invalid zip code groupings:

List<DataSourceRecord> newset = (from rst in QBModel.ResultsTable
  group rst by GetGroupRepresentation(rst.CallerZipCode) into newGroup
  select new DataSourceRecord()
  {
    State = newGroup.Select(i => i.CallerState).FirstOrDefault(),
    ZipCode = newGroup.Key,
    Calls = ???
    Exposures = ???
  }).ToList();

Grouping method:

private string GetGroupRepresentation(string zipCode)
{
    if (string.IsNullOrEmpty(zipCode) || zipCode.Length < 3)
        return "<null>";
    return zipCode.Substring(0,3);
}

New Example 2: I could also do the following I think:

List<DataSourceRecord> newset = (from rst in QBModel.ResultsTable
  group rst by rst.CallerZipCode == null || rst.CallerZipCode.Trim().Length < 3 ? "<null>" : rst.CallerZipCode.Substring(0, 3) into newGroup
  select new DataSourceRecord()
  {
    State = newGroup.Select(i => i.CallerState).FirstOrDefault(),
    ZipCode = newGroup.Key,
    Calls = ???
    Exposures = ???
  }).ToList();

I am trying to figure out what I need to change in the original query for the two counts for 'Calls' and 'Exposures' for the grouping in the new query. How and what is needed to accomplish this?

[Edit] Extension to same issue:

How to configure grouping with two or more properties. Is belwo

List<DataSourceRecord> 
    newset = (from rst in QBModel.ResultsTable
              group rst by GetGroupRepresentation(rst.CallerZipCode, rst.CallerState) into newGroup
              select new MapDataSourceRecord()
              {
                State = ToTitleCase(newGroup.Select(i => i.CallerState).FirstOrDefault()),
                StateFIPS = FipsForStateCD(newGroup.Select(i => i.CallerStateCD).FirstOrDefault()),
                ZipCode = newGroup.Key[0],
                Calls = newGroup.Where(x => x.CALL_ID > 0).Distinct().Count(),
                Exposures = newGroup.Where(x => x.CALL_ID > 0 && x.EXPO_ID > 0).Distinct().Count(),
                InfoRequests = newGroup.Where(x => x.CALL_ID > 0 && x.INFO_ID > 0).Distinct().Count(),
                Population = GetZipCode3Population(newGroup.Key[0])
              }).ToList();

The method:

    private string[] GetGroupRepresentation(string ZipCode, string State)
    {
      string ZipResult;
      string StateResult;
      if (string.IsNullOrEmpty(ZipCode) || ZipCode.Length < 3)
        ZipResult = "<null>";
      else
        ZipResult = ZipCode.Substring(0, 3);

      if (string.IsNullOrEmpty(State))
        StateResult = "<null>";
      else
        StateResult = State;

      return  new string[]{ ZipResult, State };
    }

回答1:

First about the calls:

Calls = newGroup.Where(x => x.CallerZipCode.StartsWith(newGroup.Key) && x.CALL_ID > 0).Distinct().GroupBy(g => new { g.CallerZipCode, g.CTR_ID, g.CALL_ID }).Count(),

As I understand, you want for the group the distinct number of calls where CALL_ID > 0. I don't understand why you create a new group with the zip code, the CTR_ID and the CALL_ID. If I have understood correctly, the Exposures are very similar.

List<DataSourceRecord> newset = (from rst in QBModel.ResultsTable
  group rst by GetGroupRepresentation(rst.CallerZipCode) into newGroup
  select new DataSourceRecord()
  {
    State = newGroup.Select(i => i.CallerState).FirstOrDefault(),
    ZipCode = newGroup.Key,
    Calls = newGroup.Where(x => x.CALL_ID > 0).Select(x => x.CALL_ID).Distinct().Count(),
    Exposures = newGroup.Where(x => x.CALL_ID > 0 && x.ExposureCount > 0).Distinct().Count()
  }).ToList();

If you really want to group the calls/exposures meaning you want to count the unique combinations of (CTR_ID and CALL_ID / CallerState, CTR_ID and CALL_ID), you can of course do so.

来源：https://stackoverflow.com/questions/57247012/group-linq-results-by-value-and-group-null-or-invalid-values-and-do-counts