Removing duplicates from arraylist which contain array of double

Question

I have a list which has double array whose items are geocordinates,this list has duplicate elements which i need to remove to preserve only unique values

this is what i have tried

IList<double[]> result = new List<double[]>(); /list declaration

// result gets value from a soap call 

for (int i = 0; i < result.Count; i++)
{
    for (int j = 0; j < result.Count; j++)
    {
         if (result[i][0].ToString() == result[j][0].ToString() || result[i][1].ToString() == result[j][1].ToString())
         {
             result.Remove(result[j]);
         }
    }
}

result - my list which has redundant arrays

basically, i need to remove all the arrays inside the list which has same values(x and y geocordinates)

still i have some elements in the list which gets duplicated, can anyone improve my solution please ? would be great help

same geocordinates means both x and y must be equal so change || to && — Hasan Gholamali
– Hasan Gholamali, Commented Jun 3, 2018 at 9:47
Create an array; then save data that has their condition and finally, replace the new array with Old Array. — BehrouzMoslem
– BehrouzMoslem, Commented Jun 3, 2018 at 9:58
Even if you find the right solution for your question, I would recommend to change your approach. Instead of using double[], you can define coordinates as Point class. In Point class, you can override the ToEquals method to check the duplicate. — user1672994
– user1672994, Commented Jun 3, 2018 at 10:19
Instead of using existing Point from System.Windows or System.Drawing, I would suggest to write a new class with decimal and decimal as X and Y respectively. With this approach, you will have full control over it to override ToEquals method. — user1672994
– user1672994, Commented Jun 3, 2018 at 10:32

TaW · Accepted Answer · 2018-06-03 10:29:38Z

2

This example takes the 100 in data down to 41 in dataUnique

Random r = new Random(99);
var data = new List<Tuple<decimal, decimal>>();
for (int i = 0; i < 100; i++)
{
    data.Add(new Tuple<decimal, decimal>(r.Next(7)/100m, r.Next(7)/100m));
}
var dataUnique = data.Distinct().ToList();

Wrt your code: Do note that comparing float or double will not work well if any computation has been used on those numbers as binary numbers do not allow the precision needed to do the comparisons.. - Do replace the double by decimal as a first improvement..

Using ToString() may or may not help overcome the issue; best not to rely on it..

edited Jun 3, 2018 at 10:29

answered Jun 3, 2018 at 10:16

TaW

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Comments

Hasan Gholamali · Accepted Answer · 2018-06-03 10:12:10Z

1

Try this:

result = result.GroupBy(r => new { val1 = r[0], val2 = r[1] })
               .Select(g => new double[] { g.Key.val1, g.Key.val2 }).ToList();

answered Jun 3, 2018 at 10:12

Hasan Gholamali

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Comments

Madhan Kumar · Accepted Answer · 2018-06-03 10:18:29Z

1

IList<double[]> result = new List<double[]>(); /list declaration

// result gets value from a soap call 

for (int i = 0; i < result.Count; i++)
{
    for (int j = i + 1; j < result.Count; j++)
    {
         if (result[i][0].ToString() == result[j][0].ToString() && result[i][1].ToString() == result[j][1].ToString())
         {
             result.Remove(result[j]);
             j--;
         }
    }
}

answered Jun 3, 2018 at 10:18

Madhan Kumar

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