Sorting Points

  • Thread starter Thread starter shortyes
  • Start date Start date
S

shortyes

Is there any easy way to sort a list of Points by either its X or Y or
both?

Tried
sortedlist (of String, Point) where string is Point.X & "," & Point.Y
as the key
sortedlist (of Point, Point) using the Point as the key

I could always use try and true method of a binary search algorithm
but I rather not.

It seems to be storing it but I can't seem to extract the data
 
Is there any easy way to sort a list of Points by either its X or Y or
both?

Tried
sortedlist (of String, Point) where string is Point.X & "," & Point.Y
as the key
sortedlist (of Point, Point) using the Point as the key

I could always use try and true method of a binary search algorithm
but I rather not.

It seems to be storing it but I can't seem to extract the data
Click to expand...

You could write an IComparer that knows how to compare Points by their
coordinates and pass that in to the Sort method of a list.
 
Chris Dunaway said:
You could write an IComparer that knows how to compare Points by their
coordinates and pass that in to the Sort method of a list.
Click to expand...

EG


Function CompareX(ByVal a As Point, ByVal b As Point) As Integer
Return a.X.CompareTo(b.X)
End Function

Function CompareY(ByVal a As Point, ByVal b As Point) As Integer
Return a.Y.CompareTo(b.Y)
End Function

Sub Main()

Dim points() As Point = {New Point(3, 4), New Point(1, 5), New Point(7,
2)}
Array.Sort(Of Point)(points, AddressOf CompareX)


Console.WriteLine("Array of points sorted by X")
For Each p As Point In points
Console.WriteLine(String.Format("x={0},y={1}", p.X, p.Y))
Next

Dim pointList As New List(Of Point)(points)
pointList.Sort(AddressOf CompareY)

Console.WriteLine("List of points sorted by Y")
For Each p As Point In pointList
Console.WriteLine(String.Format("x={0},y={1}", p.X, p.Y))
Next

Console.ReadKey()

End Sub



Davud
 
Dim points() As Point = {New Point(3, 4), New Point(1, 5), New Point(7,
2)}
Array.Sort(Of Point)(points, AddressOf CompareX)
Click to expand...

How does this work? I cant find a reference in the docs to an
Array.Sort method that takes that kind of delegate? I tested the code
and it works, of course, I am just at a loss to understand how?

Thanks,

Chris
 
Chris Dunaway said:
How does this work? I cant find a reference in the docs to an
Array.Sort method that takes that kind of delegate? I tested the code
and it works, of course, I am just at a loss to understand how?
Click to expand...

That's this overload

Public Shared Sub Sort(Of T) ( _
array As T(), _
comparison As Comparison(Of T) _
)
http://msdn2.microsoft.com/en-us/library/cxt053xf.aspx

Which uses the Comparison generic delegate

Public Delegate Function Comparison(Of T) ( _
x As T, _
y As T _
) As Integer
http://msdn2.microsoft.com/en-us/library/tfakywbh.aspx

David
 
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