LINQ Method - Optimization

Question

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.

I'm not sure what the purpose of the groupby and last select is, are you trying to filter distinct elements? because there are much better ways to do that. — caesay, Feb 17 '18 at 21:39
I'm trying to groupby all cols, and sum the TimesheetHours `TimesheetHours = g.Sum(s => s.TimesheetHours)` — Lee Stevens, Feb 17 '18 at 21:40
Use oledb to read into a datatable. I gave a little example the other day : https://stackoverflow.com/questions/48788682/validate-content-of-csv-file-c-sharp/48791373#comment84640949_48791373 — jdweng, Feb 17 '18 at 22:00

score 3 · Accepted Answer · answered Feb 17 '18 at 22:05

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.

many thanks! Thanks for explaining and helping me continue to learn! :) — Lee Stevens, Feb 17 '18 at 22:19

LINQ Method - Optimization

1 Answers1