choose uniqe item from list

Question

I have this list of colors in a wpf application. what I want is to random choose a color each time I call the function but I don’t want that a one color be chosen more than on time. This is my code that not doing what I want.

 var polyline = new MapPolyline();
 polyline.Stroke = GetRandomPolylineColor();

private Brush GetRandomPolylineColor()
        {
            var brushes = new Brush[] 
            {       Brushes.Blue,
                 Brushes.Black,
                 Brushes.Red,
                 Brushes.Brown,
                 Brushes.Green,
                 Brushes.HotPink,
                 Brushes.Khaki,
                 Brushes.IndianRed,
                 Brushes.LimeGreen,
                 Brushes.Orange                               
            };

            var rnd = new Random();
            return brushes[rnd.Next(brushes.Length)];
        }

Is your code currently swapping the color? or is that also one of the problems? if it changes all you should need is to make a temp variable for ur current brush, then check it for equality and go again if its the same as before — pål-jørgen valdersnes, Apr 14 '16 at 07:08
Id probably have used lists and had a master list, aka master_brushes and set brushes to the same content, and then each time picked from brushes, removed the used item, on finding 0 items, reload from master and start over again. — BugFinder, Apr 14 '16 at 07:15

score 3 · Answer 1 · edited May 23 '17 at 12:16

3

What you are describing is known as sampling without replacement. This has been answered in the SO posts Unique (non-repeating) random numbers in O(1) and Algorithm for sampling without replacement.

edited May 23 '17 at 12:16

Community

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answered Apr 14 '16 at 07:11

Wicher Visser

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choose uniqe item from list

1 Answers1