Simple question about sorting methods in VB.Net

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Permalink Reply by David Rutten on November 2, 2011 at 11:33am

Hi Thibault,

 

when you call ToArray() on a List(Of T) you get a new array instance, filled up with the same elements as the list. Any modifications to this array will pass unnoticed from the point of view of the list.

 

You need to create two arrays, sort them using the key/value approach you pasted above, then move the arrays back into the lists. The easiest way to achieve this would be:

 

'Create lists.

Dim myKeys As New List(Of Double)

Dim myValues As New List(Of Whatever)

'Fill up myKeys and myValues with whatever data you want

 

'Perform sorting step.

Dim arrKeys As Double() = myKeys.ToArray()

Dim arrValues As Whatever() = myValues.ToArray()

Array.Sort(myKeys, myValues)

 

'Put arrays back into lists.

myKeys.Clear()

myValues.Clear()

myKeys.AddRange(arrKeys)

myValues.AddRange(arrValues)

 

 

List(Of T) also supports a fair amount of sorting logic, it may be possible to achieve your goals without round-tripping to arrays.

 

--

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Thibault Schwartz on November 2, 2011 at 12:42pm

Thanks a lot for your quick and very precise answer David,

I will try that this evening.

Thanks again, 

TS.