Does my LINQ query provide distinct SampleNumbers based off the code and LINQPad output provided?-CodePudding

I'm trying to use LINQPad to see outputs of my queries I'm writing for a C# WinForms application. I'm more just confused on how to interpret the outcome on a Dump() method and what is happening behind the scenes.My intended outcome is to have one SampleNumber per group of SampleData. SampleData is coming out of the database as a string split by commas. Also, please spare me; I know how I name stuff is horrible and I'm planning to adjust once I get the data coming out correctly!

Here is my initial query:

var thinthroughoutQuery = (from a in ThicknessBlobs
                                       join b in SummaryDataItems on a.SampleNumber equals b.SampleNumber
                                       where (a.Source == "Thickness[0,0]")
                                       && b.TopBottomStatusFK == 3
                                       orderby a.PKId descending
                                       select a).Take(1000).ToList();

Here is where I attempt to take the string of SampleData, cut it at the delimiter, group by SampleNumber, and parse it as an integer:

var intThinThroughoutQuery = thinthroughoutQuery.Select(row => new { SampleNumber = row.SampleNumber, Value = row.SampleData.Split(",").Select(int.Parse) })
                .SelectMany(group => group.Value.Select(value => new { group.SampleNumber, SampleData = value })).ToArray();

Here is the output from using Dump() in LINQPad:

To me, this appears like there are not distinct SampleNumbers and that each piece of SampleData separately maps to a repeating SampleNumber.

For further clarification, I want to be able to access the data and have it be like this:

Rather than:

CodePudding user response：

You are missing GroupBy/ToLookup after flattening with SelectMany:

var intThinThroughoutQuery = thinthroughoutQuery.Select(row => new { SampleNumber = row.SampleNumber, Value = row.SampleData.Split(",").Select(int.Parse) })
    .SelectMany(group => group.Value.Select(value => new { group.SampleNumber, SampleData = value }))
    .ToLookup(row => row.SampleNumber, row => row.SampleData);