Question

I have a table (HallPlan) with fields:

Row, Seat, Width, Height, X, Y

And grouped collection by Y:

var ordered = hallPlans.GroupBy(s => s.Y).OrderBy(o => o.Key);

now I want to select max X from all minimum X for each group. For example ordered contains three groups, we have:

first group contains 3 records with X coordinates: 15, 50, 80;
second group contains: 16, 50,80;
and last group contains: 15, 40, 60;

select all min from each groupes: 15, 16, 15
and select max from the above: 16.

How can I do this with LINQ?
Thanks.

Answer 1

You can use the Min and Max functions.

class HallPlan { public int X { get; set; } }

...

var groups = new[]{
                    new []{new HallPlan{X=15},new HallPlan{X=50},new HallPlan{X=80}},
                    new []{new HallPlan{X=16},new HallPlan{X=50},new HallPlan{X=80}},
                    new []{new HallPlan{X=15},new HallPlan{X=40},new HallPlan{X=60}}
                };

var maxmin = groups.Select(g => g.Min(h => h.X)).Max(); // result is 16

groups.Select(g => g.Min(h => h.X)) will select the minimun HallPlan.X from each group, and .Max() will then return the biggest value of those.