VBA Nested Loop with Array running very slowly - Looking for Solutions - arrays

Question

I'm running a nested loop, which I've added an array to in an attempt to speed up, but it is still running fairly slowly. When I have 100 rows and 41 columns of data in the "Active" sheet and 1000 rows and 41 columns of data in the "Closed" sheet, it takes about 7 minutes to run through the code and output the data into the "CompSheet"
Sub CompareColumns()
'Turn off screen updating and automatic calculation
Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual
Dim i As Integer 'variable for the outer loop
Dim j As Integer 'variable for the inner loop
Dim ws As Worksheet 'variable for the sheet CompSheet
Dim compareLat As Byte 'variable for the column that is being compared
Dim compareLon As Byte 'variable for the column that is being compared
Dim compareLatArray As Byte
Dim compareLonArray As Byte
Dim uniqueID As String 'variable for the unique identifier
Dim ActiveSheetRows As Integer
Dim ClosedSheetRows As Integer
Dim closedArray As Variant ' variable for closed sheet data
Dim closedArrayRow As Variant
Dim activeArray As Variant ' variable for active sheet data
Dim activeArrayRow As Variant
Dim dLon As Double
Dim x As Double
Dim y As Double
Dim lat_a As Double
Dim lat_c As Double
Dim lon_a As Double
Dim lon_c As Double
Dim result As Double
Dim distance_toggle As Single
Dim distance As Single
ActiveSheetRows = Worksheets("Active").UsedRange.Rows.Count
ClosedSheetRows = Worksheets("Closed").UsedRange.Rows.Count
compareLat = 38 'change this variable to switch the column that is being compared
compareLon = 39 'change this variable to switch the column that is being compared
compareLatArray = 38 'change this variable to switch the column that is being compared
compareLonArray = 39 'change this variable to switch the column that is being compared
distance_toggle = 1.5
'Store the data from the "Closed" worksheet into the array
closedArray = Worksheets("Closed").UsedRange.Value
'Store the data from the "Active" worksheet into the array
activeArray = Worksheets("Active").UsedRange.Value
'Check if the sheet CompSheet exists, if not create it
On Error Resume Next
Set ws = ThisWorkbook.Sheets("CompSheet")
If ws Is Nothing Then
ThisWorkbook.Sheets.Add(After:=ThisWorkbook.Sheets(ThisWorkbook.Sheets.Count)).Name = "CompSheet"
'copy the header row from the "Closed" worksheet when it first creates the "CompSheet" worksheet
Worksheets("Closed").Rows(1).Copy _
Destination:=Worksheets("CompSheet").Range("A1")
'Add the column header "uniqueID" to the last cell in row 1 of the "CompSheet" worksheet
Worksheets("CompSheet").Cells(1, Worksheets("CompSheet").UsedRange.Columns.Count + 1).Value = "uniqueID"
'Add the column header "CompDistance" to the last cell in row 1 of the "CompSheet" worksheet
Worksheets("CompSheet").Cells(1, Worksheets("CompSheet").UsedRange.Columns.Count + 1).Value = "CompDistance"
End If
On Error GoTo 0
'Loop through all the rows in the "Active" worksheet starting on row 2
For i = 2 To UBound(activeArray, 1)
'Loop through the array to look up the data in the "Closed" worksheet
For j = 2 To UBound(closedArray, 1)
lat_a = activeArray(i, compareLat)
lat_c = closedArray(j, compareLatArray)
lon_a = activeArray(i, compareLon)
lon_c = closedArray(j, compareLonArray)
'Calculationg for D2R = 0.0174532925199433
'pi = 4 * Atn(1)
'D2R = pi / 180#
lat_a = 0.0174532925199433 * lat_a
lat_c = 0.0174532925199433 * lat_c
dLon = 0.0174532925199433 * (lon_c - lon_a)
x = Sin(lat_a) * Sin(lat_c) + Cos(lat_a) * Cos(lat_c) * Cos(dLon)
y = Sqr((Cos(lat_c) * Sin(dLon)) ^ 2 + (Cos(lat_a) * Sin(lat_c) - Sin(lat_a) * Cos(lat_c) * Cos(dLon)) ^ 2)
distance = WorksheetFunction.Atan2(x, y) * 3963.19
If distance <= distance_toggle Then
'Copy the row from the Closed worksheet to the CompSheet worksheet in the next available row
Worksheets("CompSheet").Rows(Worksheets("CompSheet").UsedRange.Rows.Count + 1).Insert
closedArrayRow = Worksheets("Closed").Cells(j, 1).Resize(1, UBound(closedArray, 2))
'Worksheets("CompSheet").Range("B1").Resize(UBound(closedArrayRow, 1), UBound(closedArrayRow, 2)).Value = closedArrayRow
Worksheets("CompSheet").Rows(Worksheets("CompSheet").UsedRange.Rows.Count).Resize(1, 41).Value = closedArrayRow
'Create a uniqueID by combining column 6 from both the Active and Closed worksheets with a space and "&" in between
uniqueID = activeArray(i, 5) & " " & "&" & " " & closedArray(j, 5)
'Paste the uniqueID in the next available column of the new row in the CompSheet worksheet
Worksheets("CompSheet").Cells(Worksheets("CompSheet").UsedRange.Rows.Count, compareLon + 1).Value = uniqueID
'Paste the distance value in the corresponding column of the new row in the CompSheet worksheet
Worksheets("CompSheet").Cells(Worksheets("CompSheet").UsedRange.Rows.Count, compareLon + 2).Value = distance
End If
Next j
Next i
'Formatting "CompSheet" Data
Worksheets("CompSheet").Columns.AutoFit
Worksheets("CompSheet").Range("AO:AO").NumberFormat = "#,##0.0"
Worksheets("CompSheet").UsedRange.Font.Bold = False
Worksheets("CompSheet").Cells(1, 1).EntireRow.Font.Bold = True
'Turn on screen updating and automatic calculation
Application.ScreenUpdating = True
Application.Calculation = xlCalculationAutomatic
End Sub
I added the array's to try and speed things up but I'm not sure I've implemented them properly. I've also added some other code to help improve the speed (as suggested by OpenAI ChatGPT), such as:
Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual
Any help would be great appreciated.
UPDATE: See below google drive link for the actual excel file. I've run my code and it took 8 minutes. Eventually, I'd like to scale this up to a dataset about 500 times this size. Which would take 60 hours to run based on a linear time calculation.
https://drive.google.com/file/d/1GfR5RbWcHFQC-5oY9izDOQWbzZkvBwXi/view?usp=share_link
What I'm trying to do is compare real estate listings (properties), properties that are currently listed for sale in the "Active" sheet to ones that are already sold, in the "Closed" sheet. For every property (row) in the "Active" sheet, I need the code to check over every sold property in the "Closed" sheet based on the distance toggle and if the sold property is within the specified distance (2 miles) then I want to copy the sold listing row from the "Closed" sheet into the "CompSheet" and also paste the Unique ID (Both addresses concatenated) and the 'distance' variable, for that comp.

Answer 1

Should take less than 10 seconds
Option Explicit
Sub CompareColumns()
'change these variable to switch the column that is being compared
Const compareLat = 38 'AL
Const compareLon = 39 'AM
Const compareLatArray = 38 'AL
Const compareLonArray = 39 'AM
Const distance_toggle = 1.5
Dim wb As Workbook
Dim wsClosed As Worksheet, wsActive As Worksheet, wsComp As Worksheet
Dim n As Long, rComp As Long, colsClosed As Long, t0 As Single: t0 = Timer
Set wb = ThisWorkbook
With wb
Set wsActive = .Sheets("Active")
Set wsClosed = .Sheets("Closed")
n = .Sheets.Count
On Error Resume Next
Set wsComp = .Sheets("CompSheet")
On Error GoTo 0
If wsComp Is Nothing Then
Set wsComp = .Sheets.Add(After:=.Sheets(n))
With wsComp
.Name = "CompSheet"
'copy the header row from the "Closed" worksheet
'when it first creates the "CompSheet" worksheet
wsClosed.Rows(1).Copy .Range("A1")
'Add the column header "uniqueID" and "CompDistance"
'to the end of row 1 of the "CompSheet" worksheet
colsClosed = .UsedRange.Columns.Count
.Cells(1, colsClosed + 1).Value = "uniqueID"
.Cells(1, colsClosed + 2).Value = "CompDistance"
'Formatting "CompSheet" Data
.Columns.AutoFit
.Range("AO:AO").NumberFormat = "#,##0.0"
.UsedRange.Font.Bold = False
.Cells(1, 1).EntireRow.Font.Bold = True
End With
Else
colsClosed = wsClosed.UsedRange.Columns.Count
End If
rComp = wsComp.UsedRange.Rows.Count + 1
End With
'Store the data from the "Active" and "Closed"
'worksheet into the array
Dim arActive, arClosed
arActive = wsActive.UsedRange.Value
arClosed = wsClosed.UsedRange.Value
Dim i As Long, j As Long, k As Long
Dim lat_a As Double, lon_a As Double, lat_c As Double, lon_c As Double
Dim x As Double, y As Double, dLon As Double, distance As Double
Dim uniqueID As String
'Calculationg for D2R = 0.0174532925199433
'pi = 4 * Atn(1)
'D2R = pi / 180#
Const FACTOR As Double = 1.74532925199433E-02
' dimension max possible rows
Dim arComp, z As Long
z = UBound(arActive) * UBound(arClosed)
ReDim arComp(1 To z, 1 To colsClosed + 2)
rComp = 0
'Loop through all the rows in the "Active" worksheet starting on row 2
For i = 2 To UBound(arActive, 1)
lat_a = arActive(i, compareLat) * FACTOR
lon_a = arActive(i, compareLon)
'Loop through the array to look up the data in the "Closed" worksheet
For j = 2 To UBound(arClosed, 1)
lat_c = arClosed(j, compareLatArray) * FACTOR
lon_c = arClosed(j, compareLonArray)
dLon = FACTOR * (lon_c - lon_a)
x = Sin(lat_a) * Sin(lat_c) + Cos(lat_a) * Cos(lat_c) * Cos(dLon)
y = Sqr((Cos(lat_c) * Sin(dLon)) ^ 2 + (Cos(lat_a) * Sin(lat_c) - Sin(lat_a) * Cos(lat_c) * Cos(dLon)) ^ 2)
distance = WorksheetFunction.Atan2(x, y) * 3963.19
If distance <= distance_toggle Then
'Create a uniqueID by combining column 6 from
'both the Active and Closed worksheets
'with a space and "&" in between
uniqueID = arActive(i, 5) & " " & "&" & " " & arClosed(j, 5)
'Copy the row from the Closed worksheet to the
'CompSheet worksheet in the next available row
'Paste the uniqueID and distance in the next available column
'of the new row in the CompSheet worksheet
rComp = rComp + 1
For k = 1 To colsClosed
arComp(rComp, k) = arClosed(j, k)
Next
arComp(rComp, k) = uniqueID
arComp(rComp, k + 1) = distance
End If
Next j
Next i
'Turn off screen updating and automatic calculation
Application.Calculation = xlCalculationManual
Application.ScreenUpdating = False
' result
Dim rngComp As Range
With wsComp
Set rngComp = .Cells(.UsedRange.Rows.Count + 1, "A")
Set rngComp = rngComp.Resize(rComp, colsClosed + 2)
rngComp = arComp
End With
'Turn on screen updating and automatic calculation
Application.ScreenUpdating = True
Application.Calculation = xlCalculationAutomatic
MsgBox "Data written " & rngComp.Address, vbInformation, "Took " & Format(Timer - t0, "0.00 secs")
End Sub

Answer 2

One thing I found so far that is not needed is this:
Worksheets("CompSheet").Rows(Worksheets("CompSheet").UsedRange.Rows.Count + 1).Insert
This looks like you're adding a row to the bottom. You don't have to add rows to the bottom, they're already there - just comment that out and add 1 to your "copy" statement, Rows.Count + 1.
Worksheets("CompSheet").Rows(Worksheets("CompSheet").UsedRange.Rows.Count + 1).Resize(1, 41).Value = closedArrayRow

Answer 3

This should be faster. Compiles, but untested.
Use of worksheet references makes your code cleaner.
Swapped out the WorksheetFunction call for a faster VBA version.
Skipped the Insert when adding data to the comp sheet (as already suggested by Nick).
Use Const for fixed values
Avoid UsedRange since it can be unreliable/unpredictable
Sub CompareColumns()
Const NUM_COLS As Long = 39
Const ID_COL As Long = 40
Const DIST_COL As Long = 41
Const COL_ACT_LAT As Long = 38
Const COL_ACT_LON As Long = 39
Const COL_CLS_LAT As Long = 38
Const COL_CLS_LON As Long = 39
Const DIST_TOGGLE As Double = 1.5
Dim wb As Workbook, wsActive As Worksheet, wsClosed As Worksheet, wsComp As Worksheet
Dim rngClosed As Range, rngActive As Range
Dim i As Long, j As Long
Dim closedArray As Variant, activeArray As Variant
Dim lat_a As Double, lat_c As Double, lon_a As Double, lon_c As Double
Dim distance As Double, lastRw As Long, destRw As Range
Set wb = ThisWorkbook
Set wsActive = wb.Worksheets("Active")
'if your data has no empty rows or columns
Set rngActive = wsActive.Range("A1").CurrentRegion.Resize(, NUM_COLS)
activeArray = rngActive.Value
Set wsClosed = wb.Worksheets("Closed")
Set rngClosed = wsClosed.Range("A1").CurrentRegion.Resize(, NUM_COLS)
closedArray = rngClosed.Value
'add the comparison sheet if not already present
On Error Resume Next 'ignore error if sheet is missing
Set wsComp = wb.Worksheets("CompSheet")
On Error GoTo 0 'stop ignoring errors as soon as it's no longer needed....
If wsComp Is Nothing Then
Set wsComp = wb.Worksheets.Add(After:=wb.Worksheets(wb.Worksheets.Count))
wsComp.Name = "CompSheet"
wsClosed.Range("A1").Resize(1, NUM_COLS).Copy wsComp.Range("A1")
wsComp.Cells(1, ID_COL).Value = "uniqueID"
wsComp.Cells(1, DIST_COL).Value = "CompDistance"
lastRw = 1
Else
'find last row with any data
lastRw = wsComp.Cells.Find(What:="*", SearchOrder:=xlByRows, _
SearchDirection:=xlPrevious).Row
End If
Set destRw = wsComp.Rows(lastRw + 1) 'first empty row on comp sheet
For i = 2 To UBound(activeArray, 1) 'loop "active" array
lat_a = activeArray(i, COL_ACT_LAT) 'you can read these in the outer loop
lon_a = activeArray(i, COL_ACT_LON)
For j = 2 To UBound(closedArray, 1) 'loop "closed" array
lat_c = closedArray(j, COL_CLS_LAT)
lon_c = closedArray(j, COL_CLS_LON)
distance = DistanceCalc(lat_a, lon_a, lat_c, lon_c)
If distance <= DIST_TOGGLE Then
destRw.Cells(1).Resize(1, NUM_COLS).Value = rngClosed.Rows(j).Value
destRw.Cells(ID_COL).Value = activeArray(i, 5) & " " & "&" & " " & closedArray(j, 5)
destRw.Cells(DIST_COL).Value = distance
Set destRw = destRw.Offset(1, 0)
End If
Next j
Next i
With wsComp 'Formatting "CompSheet" Data
.Columns.AutoFit
.Range("AO:AO").NumberFormat = "#,##0.0"
.UsedRange.Font.Bold = False
.Cells(1, 1).EntireRow.Font.Bold = True
End With
End Sub
'Miles between (latA,lonA) and (latB,lonB)
Function DistanceCalc(latA As Double, lonA As Double, latB As Double, lonB As Double) As Double
Const RAD_MULT As Double = 1.74532925199433E-02
Dim dlon As Double, x As Double, y As Double
latA = latA * RAD_MULT
latB = latB * RAD_MULT
dlon = RAD_MULT * (lonB - lonA)
x = Sin(latA) * Sin(latB) + Cos(latA) * Cos(latB) * Cos(dlon)
y = Sqr((Cos(latB) * Sin(dlon)) ^ 2 + (Cos(latA) * Sin(latB) - Sin(latA) * Cos(latB) * Cos(dlon)) ^ 2)
'DistanceCalc = WorksheetFunction.Atan2(x, y) * 3963.19
DistanceCalc = ArcTan2(x, y) * 3963.19 'VBA version is faster
End Function
'VBA version of WorksheetFunction.Atan2
Function ArcTan2(x As Double, y As Double) As Double
Const PI As Double = 3.14159265358979
Const PI_2 As Double = 1.5707963267949
Select Case x
Case Is > 0
ArcTan2 = Atn(y / x)
Case Is < 0
ArcTan2 = Atn(y / x) + PI * Sgn(y)
If y = 0 Then ArcTan2 = ArcTan2 + PI
Case Is = 0
ArcTan2 = PI_2 * Sgn(y)
End Select
End Function

Answer 4

There are a few basic things you can do to speed code up. The easiest is to disable screen updating and calculations. You can use error handling to ensure they get re-enabled.
Sub MyFasterProcess()
Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual
On Error GoTo Finally
Call MyLongRunningProcess()
Finally:
Application.ScreenUpdating = True
Application.Calculation = xlCalculationAutomatic
If Err > 0 Then Err.Raise Err
End Sub
Some people like to put that into some helper functions, or even a class to manage the state over several processes.
The most common culprit for long running processes is reading from and writing to cells. It is significantly faster to read an array than it is to read individual cells in the range.
Consider the following:
Sub SlowReadWrite()
Dim src As Range
Set src = Range("A1:AA100000")
Dim c As Range
For Each c In src
c.Value = c.Value + 1
Next c
End Sub
This will take a very, very long time. Now let's do it with an array. Read once. Write once. No need to disable screen updating or set calculation to manual either. This will be just as fast with them on.
Sub FastReadWrite()
Dim src As Range
Set src = Range("A1:AA100000")
'Read once.
Dim vals() As Variant
vals = r.Value
Dim r As Long, c As Long
For r = 1 To UBound(vals, 1)
For c = 1 To UBound(vals, 2)
vals(r, c) = vals(r, c) + 1
Next c
Next r
'Write once.
src.Value = vals
End Sub
Your code looks like it's still performing read / write actions in the loop which is what is slowing you down.