Sorting Points

[shortyes@gmail.com]

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

[Chris Dunaway]

Re: Sorting Points

On Feb 26, 7:13 am, short...@gmail. com wrote:

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

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.

[David Browne]

Re: Sorting Points



"Chris Dunaway" <dunawayc@gmail .comwrote in message
news:1172499482 .289195.6670@m5 8g2000cwm.googl egroups.com...

On Feb 26, 7:13 am, short...@gmail. com wrote:

>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

>
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.
>
>

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

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

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

Console.ReadKey ()

End Sub



Davud

[Chris Dunaway]

Re: Sorting Points

On Feb 26, 10:05 am, "David Browne" <davidbaxterbro wne no potted
m...@hotmail.co mwrote:

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

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

[David Browne]

Re: Sorting Points



"Chris Dunaway" <dunawayc@gmail .comwrote in message
news:1172528869 .896639.46820@m 58g2000cwm.goog legroups.com...

On Feb 26, 10:05 am, "David Browne" <davidbaxterbro wne no potted
m...@hotmail.co mwrote:

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

>
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?
>

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