CODEWITHSUNDEEP
c#linqcsvperformance-testing
Lee Stevens
Lee Stevens

Reputation: 482

LINQ Method - Optimization

I'm reading a CSV file splitting it into cols, then grouping into a new class.

It looks clunky just wondering is there is a more simple method for instance like not selecting them into the class first:

EDIT: so to clarify I'm trying to get the TimesheetHours grouped by all the other columns. 

var rowList = csvFile.Rows.Select(row => row.Split(','))
    .Select(cols => new UtilisationRow {
        UploadId = savedUpload.Id,
        FullName = cols[0],
        TimesheetWorkDateMonthYear = Convert.ToDateTime(cols[1]),
        TimesheetTaskJobnumber = cols[2],
        TimesheetWorktype = cols[3],
        TimesheetHours = Convert.ToDouble(cols[4]),
        TimesheetOverhead = cols[5]
    })
    .GroupBy(d => new {
        d.FullName,
        d.TimesheetWorkDateMonthYear,
        d.TimesheetTaskJobnumber,
        d.TimesheetWorktype,
        d.TimesheetOverhead
    })
    .Select(g => new UtilisationRow {
        FullName = g.First().FullName,
        TimesheetWorkDateMonthYear = g.First().TimesheetWorkDateMonthYear,
        TimesheetTaskJobnumber = g.First().TimesheetTaskJobnumber,
        TimesheetWorktype = g.First().TimesheetWorktype,
        TimesheetHours = g.Sum(s => s.TimesheetHours),
        TimesheetOverhead = g.First().TimesheetOverhead
    })
    .ToList();

Many thanks, Lee.

Upvotes: 0

Views: 46

Answers (1)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726569

The two problems in your code are that you call First() repeatedly on a group, while you should retrieve that same data from group's key, and that you are using UtilisationRow in the first Select, which should use an anonymous type instead:

var rowList = csvFile.Rows.Select(row => row.Split(','))
    .Select(cols => new {
        UploadId = savedUpload.Id,
        FullName = cols[0],
        TimesheetWorkDateMonthYear = Convert.ToDateTime(cols[1]),
        TimesheetTaskJobnumber = cols[2],
        TimesheetWorktype = cols[3],
        TimesheetHours = Convert.ToDouble(cols[4]),
        TimesheetOverhead = cols[5]
    })
    .GroupBy(d => new {
        d.FullName,
        d.TimesheetWorkDateMonthYear,
        d.TimesheetTaskJobnumber,
        d.TimesheetWorktype,
        d.TimesheetOverhead
    })
    .Select(g => new UtilisationRow {
        FullName = g.Key.FullName,
        TimesheetWorkDateMonthYear = g.Key.TimesheetWorkDateMonthYear,
        TimesheetTaskJobnumber = g.Key.TimesheetTaskJobnumber,
        TimesheetWorktype = g.Key.TimesheetWorktype,
        TimesheetHours = g.Sum(s => s.TimesheetHours),
        TimesheetOverhead = g.Key.TimesheetOverhead
    })
    .ToList();

Now the "pipeline" of your method looks pretty clean:

  • The first Select does the initial parsing into a temporary record
  • GroupBy bundles matching records into a group
  • The final Select produces records of the required type.

Upvotes: 3

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