Sorting a list by three parameters (C#)

Question

I have this list called "Block". Each item has four parts being a string called "block", and three floats for each coordinate:

 public class Block : IComparable<Block>
 {
     public string block;
     public float xLocation;
     public float yLocation;
     public float zLocation;
     
     public Block (string newBlock, float newXLocation, float newYLocation, float newZLocation)
     {
         block = newBlock;
         xLocation = newXLocation;
         yLocation = newYLocation;
         zLocation = newZLocation;    
     }
 }

I want to order the blocks first by lowest x value, then lowest y value, and finally lowest z value.

So if I had this in the list:

"Stone", -20, 30, 15
"Slope", -20, 20, 50
"Stone", 40, 5, 0
"Slope", -20, 20, 10

It would end up like this:

"Slope", -20, 20, 10
"Slope", -20, 20, 50
"Stone", -20, 30, 15
"Stone", 40, 5, 0

Try to keep in mind I'm still not that good at Unity so if you can, try to provide some explanation on what the code is doing. Also I prefer C#.

Thanks in advance!

Answer 1

Best Answer

Answer by LessThanEpic · Jan 27, 2015 at 09:58 PM

Your block class will need to have a CompareTo method. It would probably look something like this:

 public int CompareTo(object otherObject)
 {
     Block otherBlock = (Block) otherObject;
     
     if(this.xLocation < otherBlock.xLocation)
     {
         return -1;
     }
     else if(this.xLocation > otherBlock.xLocation)
     {
         return 1;
     }
     
     //the x matched, so lets check y
     if(this.yLocation < otherBlock.yLocation)
     {
         return -1;
     }
     else if(this.yLocation > otherBlock.yLocation)
     {
         return 1;
     }
     
     //the x and y matched, so lets check z
     if(this.zLocation < otherBlock.zLocation)
     {
         return -1;
     }
     else if(this.zLocation > otherBlock.zLocation)
     {
         return 1;
     }
     
     //everything matched, the two blocks are equal
     return 0;
 
 }

Then you could have an list of Blocks and just call Sort() on the list. If you need more details on implementing IComparable I'd check out this tutorial:

http://www.codeproject.com/Articles/42839/Sorting-Lists-using-IComparable-and-IComparer-Inte

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Calvin_And_Hobbies · Jan 28, 2015 at 03:02 PM 0

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Thanks! That looks like it should do what I want.

Calvin_And_Hobbies · Jan 29, 2015 at 02:47 AM 0

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I'm getting a weird error message when I try the code: Assets/Scripts/Editor Scripts/EditorButtons.cs(7,14): error CS0535: Block' does not implement interface member System.IComparable.CompareTo(Block)'

Any ideas?

LessThanEpic · Jan 29, 2015 at 02:57 AM 0

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Change your method signature from

 public int CompareTo(Object otherBlock)

to

  public int CompareTo(Block otherBlock)

Calvin_And_Hobbies · Jan 29, 2015 at 03:07 AM 0

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Ok that bug was fixed, but now I have a new problem. I want to be able to add objects to a new list via button. Can I create a list in one function and add to it in another?

Calvin_And_Hobbies · Jan 29, 2015 at 03:28 AM 0

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Never mind, I just made the variable at the beginning of the class.

Sorting a list by three parameters (C#)

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