Evenly Distributing Arrary Elements Across Multiple Columns in Excel VBA - excel

Question

first time poster, long time reader.
Apologies if this is hard to follow.
I have a spreadsheet which has a list of first names and last names. What I am wanting to do is take all of the first names which have the same last name and place them, evenly(ish) and separated by a comma, into the 3 reference columns in the same spreadsheet for example;
Example of Completed Sheet
I would like to do this in VBA because there are 200+ names and growing, and later the code will use this information to create and populate more workbooks.
So far, what I have works for all last names which have 3 or less first names (ie; one per column) but I cannot get it to work for last names where there are more than 3 first names.
My thought was to read all of the names into an array, split out the elements which have more than 3 names into another array, join these together separated by a comma, to then be transferred to the relevant column on the sheet.
However for some reason, I cannot get it to output more than one name into the column.
I have had a few attempts at this, but this is my latest attempt;
Private Sub cmdUpdate_Click()
Dim i As Long
Dim j As Long
Dim k As Long
Dim l As Long
Dim m As Long
Dim namesPerCol As Long
Dim strLastNameMatches As String
Dim arrNames() As String
Dim arrMultiNames(3) As String
Application.ScreenUpdating = False
With ActiveSheet
'Finds the last row with data in it
lngLastRow = .Cells(.Rows.count, "A").End(xlUp).Row
End With
'Sort the Columns
Columns("A:E").Sort key1:=Range("A1"), Header:=xlYes
'Loop through the LastNames
For i = 2 To lngLastRow
'Second loop through the LastNames
For j = 2 To lngLastRow
'If the last name matches
If Cells(i, 2).Value = Cells(j, 2).Value Then
'If the cell is empty then
If Range("C" & i).Value = "" Then
'Place the name in colA into colC
Range("C" & i).Value = Range("A" & j).Value
Else
'If the cell is not empty, then place a comma and space and then the value from colA
Range("C" & i).Value = Range("C" & i).Value & ", " & Range("A" & j).Value
End If
End If
Next j
Next i
For i = 2 To lngLastRow
strLastNameMatches = Range("C" & i).Value
arrNames = Split(strLastNameMatches, ", ")
If UBound(arrNames) > 2 Then
namesPerCol = UBound(arrNames) / 3
For l = 0 To 1
For k = LBound(arrNames) To namesPerCol
arrMultiNames(l) = arrNames(k) & ", "
Next k
Next l
For m = LBound(arrMultiNames) To UBound(arrMultiNames)
Select Case m
Case 0
Range("C" & i).Value = arrMultiNames(m)
Case 1
Range("D" & i).Value = arrMultiNames(m)
Case 2
Range("E" & i).Value = arrMultiNames(m)
End Select
Next m
Else
For j = LBound(arrNames) To UBound(arrNames)
Select Case j
Case 0
Range("C" & i).Value = arrNames(j)
Case 1
Range("D" & i).Value = arrNames(j)
Case 2
Range("I" & i).Value = arrNames(j)
End Select
Next j
End If
Next i
Application.ScreenUpdating = True
End Sub
Apologies for the poor quality coding, I will work on tiding it up once it is all working.
Any help I can get to get this code splitting out the names evenly across the three columns will be greatly appreciated

Answer 1

This task might be simpler if you could store your data into a more tree-like structure. There are many ways to do this; I've used the Collection object as it's easy to handle an unknown number of items. Basically, there are collections within a collection, ie one collection of first names for each last name.
The sample below uses very rudimentary distribution code (which is also hard-coded to a split of 3), but the point is that iterating through and down the tree is far simpler:
Dim lastList As Collection, firstList As Collection
Dim lastText As String, firstText As String
Dim data As Variant, last As Variant, first As Variant
Dim output() As Variant, dist(1 To 3) As Long
Dim str As String
Dim r As Long, c As Long, i As Long
'Read data into an array
With Sheet1
data = .Range(.Range("A1"), .Cells(.Rows.Count, "B").End(xlUp)).Value2
End With
'Create lists of unique lastnames containing the firstnames
Set lastList = New Collection
For r = 2 To UBound(data, 1)
firstText = CStr(data(r, 1))
lastText = CStr(data(r, 2))
Set firstList = Nothing
On Error Resume Next
Set firstList = lastList(lastText)
On Error GoTo 0
If firstList Is Nothing Then
Set firstList = New Collection
lastList.Add firstList, lastText
End If
firstList.Add firstText
Next
'Write results to sheet
ReDim output(1 To UBound(data, 1) - 1, 1 To 3)
For r = 2 To UBound(data, 1)
lastText = CStr(data(r, 2))
Set firstList = lastList(lastText)
'Calculate the distribution
dist(3) = firstList.Count / 3 'thanks #Comitern
dist(2) = dist(3)
dist(1) = firstList.Count - dist(2) - dist(3)
i = 1: c = 1: str = ""
For Each first In firstList
str = str & IIf(i > 1, ", ", "") & first
i = i + 1
If i > dist(c) Then
output(r - 1, c) = str
i = 1: c = c + 1: str = ""
End If
Next
Next
Sheet1.Range("C2").Resize(UBound(output, 1), UBound(output, 2)).Value = output