Median function in report builder 3.0 - report

Question

I need to perform median calculation in MS Report Builder 3.0, could anyone explain how I could achieve it considering my original value are
Region - Etab- Value
Abc - Def - 10
Abc - Def - 12
Ged - Tae - 1
I need to group by Region and Etab.
I've managed to get the proper values using hashtable the following way :
Dim theHashTable As New System.Collections.Hashtable
Function AddValue(theRapport As String, theRegion As String, theEtab As String, theRow As String, theValue As String) As Integer
Dim num As Integer
num = 0
If (theHashTable Is Nothing) Then
theHashTable = New System.Collections.Hashtable
End If
If Integer.TryParse(theValue, num) Then
If (num >= 0) Then
If (theHashTable.ContainsKey(theRapport)) Then
Dim regionHT As New System.Collections.Hashtable
regionHT = theHashTable(theRapport)
If (regionHT.ContainsKey(theRegion)) Then
Dim etabHT As New System.Collections.Hashtable
etabHT = regionHT(theRegion)
If (etabHT.ContainsKey(theEtab)) Then
Dim valueHT As New System.Collections.Hashtable
valueHT = etabHT(theEtab)
If (Not valueHT.ContainsKey(theRow)) Then
valueHT.Add(theRow, theValue)
End If
etabHT(theEtab) = valueHT
Else
Dim valueHT As New System.Collections.Hashtable
valueHT.Add(theRow, theValue)
etabHT.Add(theEtab, valueHT)
End If
regionHT(theRegion) = etabHT
Else
Dim etabHT As New System.Collections.Hashtable
Dim valueHT As New System.Collections.Hashtable
valueHT.Add(theRow, theValue)
etabHT.Add(theEtab, valueHT)
regionHT.Add(theRegion, etabHT)
End If
theHashTable(theRapport) = regionHT
Else
Dim regionHT As New System.Collections.Hashtable
Dim etabHT As New System.Collections.Hashtable
Dim valueHT As New System.Collections.Hashtable
valueHT.Add(theRow, theValue)
etabHT.Add(theEtab, valueHT)
regionHT.Add(theRegion, etabHT)
theHashTable.Add(theRapport, regionHT)
End If
End If
End If
Return num
End Function
Function GetMedian(theRapport As String, theRegion As String, theEtab As String) As String
Dim arrayInt As New System.Collections.ArrayList
arrayInt = GetArray(theRapport, theRegion, theEtab)
arrayInt.Sort()
Dim mid As Double = (arrayInt.Count - 1) / 2.0
Dim midInt As Integer = mid
Dim mid2Int As Integer = mid + 0.5
If arrayInt.Count >= 2 Then
Return ((arrayInt(midInt) + arrayInt(mid2Int)) / 2).ToString()
ElseIf arrayInt.Count = 1 Then
Return arrayInt(0)
Else
Return ""
End If
End Function
Function GetQ1(theRapport As String, theRegion As String, theEtab As String) As String
Dim arrayInt As New System.Collections.ArrayList
arrayInt = GetArray(theRapport, theRegion, theEtab)
arrayInt.Sort()
Dim taille As Integer = arrayInt.Count
If (taille = 1) Then
Return arrayInt(0)
ElseIf ((taille Mod 2) = 0 And taille > 0) Then
Dim mid1 As Integer = taille / 2
Dim midmid As Integer = mid1 / 2
If (mid1 Mod 2 = 0) Then
Return ((arrayInt(midmid - 1) + arrayInt(midmid)) / 2).ToString()
Else
Return (arrayInt(midmid)).ToString()
End If
ElseIf (taille = 1) Then
Return arrayInt(1)
ElseIf ((taille - 1) Mod 4 = 0) Then
Dim n As Integer = (taille - 1) / 4
Return ((arrayInt(n - 1) * 0.25 + arrayInt(n) * 0.75)).ToString()
ElseIf ((taille - 3) Mod 4 = 0) Then
Dim n As Integer = (taille - 3) / 4
Return ((arrayInt(n) * 0.75 + arrayInt(n + 1) * 0.25)).ToString()
Else
Return ""
End If
End Function
Function GetQ3(theRapport As String, theRegion As String, theEtab As String) As String
Dim arrayInt As New System.Collections.ArrayList
arrayInt = GetArray(theRapport, theRegion, theEtab)
arrayInt.Sort()
Dim taille As Integer = arrayInt.Count
If (taille = 1) Then
Return arrayInt(0)
ElseIf ((taille Mod 2) = 0 And taille > 0) Then
Dim mid1 As Integer = taille / 2
Dim midmid As Integer = mid1 / 2
If (mid1 Mod 2 = 0) Then
Return ((arrayInt(mid1 + midmid - 1) + arrayInt(mid1 + midmid)) / 2).ToString()
Else
Return (arrayInt(mid1 + midmid)).ToString()
End If
ElseIf (taille = 1) Then
Return arrayInt(1)
ElseIf ((taille - 1) Mod 4 = 0) Then
Dim n As Integer = (taille - 1) / 4
Return ((arrayInt(3 * n) * 0.75 + arrayInt(3 * n + 1) * 0.25)).ToString()
ElseIf ((taille - 3) Mod 4 = 0) Then
Dim n As Integer = (taille - 3) / 4
Return ((arrayInt(3 * n + 1) * 0.25 + arrayInt(3 * n + 2) * 0.75)).ToString()
Else
Return ""
End If
End Function
Function GetArray(theRapport As String, theRegion As String, theEtab As String) As System.Collections.ArrayList
Dim arrayInt As New System.Collections.ArrayList
If (theHashTable Is Nothing Or theHashTable.Count = 0) Then
Return arrayInt
Else
If (theHashTable.ContainsKey(theRapport)) Then
Dim regionHT As System.Collections.Hashtable
regionHT = theHashTable(theRapport)
If (theRegion = "" And theEtab = "") Then
For Each value As System.Collections.Hashtable In regionHT.Values
For Each value2 As System.Collections.Hashtable In value.Values
For Each valeur As Integer In value2.Values
arrayInt.Add(valeur)
Next
Next
Next
ElseIf (regionHT.ContainsKey(theRegion) And theEtab = "") Then
Dim etabHT As System.Collections.Hashtable
etabHT = regionHT(theRegion)
For Each value As System.Collections.Hashtable In etabHT.Values
For Each valeur As Integer In value.Values
arrayInt.Add(valeur)
Next
Next
ElseIf (regionHT.ContainsKey(theRegion) And theEtab <> "") Then
Dim etabHT As System.Collections.Hashtable
etabHT = regionHT(theRegion)
If Not (etabHT Is Nothing Or etabHT.Count = 0) Then
If (etabHT.ContainsKey(theEtab)) Then
Dim valuesHT As System.Collections.Hashtable
valuesHT = etabHT(theEtab)
For Each value As Integer In valuesHT.Values
arrayInt.Add(value)
Next
End If
End If
End If
End If
Return arrayInt
End If
End Function
Function PrintArray(theRapport As String, theRegion As String, theEtab As String) As String
Dim arrayInt As New System.Collections.ArrayList
arrayInt = GetArray(theRapport, theRegion, theEtab)
Dim str As String = ""
If (arrayInt.Count > 0) Then
str = String.Join(" | ", arrayInt.ToArray)
Else
str = " "
End If
Return str
End Function
The first hashtable is for different tables of the report needing the median.
I then use the following command to add value
Code.AddValue("3_2",Fields!Region.Value,Fields!Etablissement.Value,Fields!rowNumber.Value,Fields!Value.Value)
Then I get the median using the expressions
=Code.GetMedian("3_2", Fields!Region.Value,Fields!Etablissement.Value)
=Code.GetMedian("3_2", Fields!Region.Value,"")
=Code.GetMedian("3_2", "","")
I've tried placing the AddValue fonction on a hidden table and in the summary row of the tables.
I get the proper value but as soon as I expand or collapse a row everything is change to blank. How can I keep the value or where could I put the AddValue function to make sure it is called on every action, for every table in the report ?
Thanks