LINQ - max of all columns - create single "row"-CodePudding

Want to do this but as a single expression:

var maxYearVolumes = volumes.Where(v => v.YEAR == maxYear);
maxYearVolumes.Max(v => v.JAN_VOLUME);
maxYearVolumes.Max(v => v.FEB_VOLUME);
maxYearVolumes.Max(v => v.MAR_VOLUME);
maxYearVolumes.Max(v => v.APR_VOLUME);
maxYearVolumes.Max(v => v.MAY_VOLUME);
maxYearVolumes.Max(v => v.JUN_VOLUME);
maxYearVolumes.Max(v => v.JUL_VOLUME);
maxYearVolumes.Max(v => v.AUG_VOLUME);
maxYearVolumes.Max(v => v.SEP_VOLUME);
maxYearVolumes.Max(v => v.OCT_VOLUME);
maxYearVolumes.Max(v => v.NOV_VOLUME);
maxYearVolumes.Max(v => v.DEC_VOLUME);

Need a single "row" with these properties filled in with the max of each.

CodePudding user response：

As mentioned by @juharr in the comments, you can group by a constant, then take the max of each value

var maxYearVolumes = volumes
    .Where(v => v.YEAR == maxYear)
    .GroupBy(v => 1)
    .Select(g => new {
        Jan = g.Max(v => v.JAN_VOLUME),
        Feb = g.Max(v => v.FEB_VOLUME),
        Mar = g.Max(v => v.MAR_VOLUME),
        Apr = g.Max(v => v.APR_VOLUME),
        May = g.Max(v => v.MAY_VOLUME),
        Jun = g.Max(v => v.JUN_VOLUME),
        Jul = g.Max(v => v.JUL_VOLUME),
        Aug = g.Max(v => v.AUG_VOLUME),
        Sep = g.Max(v => v.SEP_VOLUME),
        Oct = g.Max(v => v.OCT_VOLUME),
        Nov = g.Max(v => v.NOV_VOLUME),
        Dec = g.Max(v => v.DEC_VOLUME),
    })
    .First();

If you are using Linq-To-Objects and are worried about performance, you can use .Aggregate instead, but it may be easier to just write a normal foreach loop.