Question

I have a list of float points as following:

wayPoints = (new PointF[] { 
new PointF(18, 0), 
new PointF(18,0), 
new PointF(55, 155),
new PointF(55, 155),
new PointF(55, 155),
new PointF(55, 155),
new PointF(55, 0),
new PointF(55, 230)}).ToList();

I want to use Lambda Expressions in which the same points removed from list but one of those same points stays in the list

Output:

wayPoints = 
(new PointF[] { 
 new PointF(18, 0),
 new PointF(55, 155),
 new PointF(55, 0),
 new PointF(55, 230)}
).ToList();

How should I write my commands in Lambda Expressions?

Answer 1

If just what a list of points then you can do this (No need for first doing a array and the ToList()):

var wayPoints = new List<PointF>{ 
    new PointF(18, 0), 
    new PointF(18,0), 
    new PointF(55, 155),
    new PointF(55, 155),
    new PointF(55, 155),
    new PointF(55, 155),
    new PointF(55, 0),
    new PointF(55, 230)
};

If you want the unique points. The you can use Distinct. Like this:

var wayPoints = (new PointF[] { 
new PointF(18, 0), 
new PointF(18,0), 
new PointF(55, 155),
new PointF(55, 155),
new PointF(55, 155),
new PointF(55, 155),
new PointF(55, 0),
new PointF(55, 230)}).ToList();
var uniquePoints=wayPoints.Distinct().ToList();