VBA Multidimensional Arrays


Example

Multidimensional Arrays

As the name indicates, multi dimensional arrays are arrays that contain more than one dimension, usually two or three but it can have up to 32 dimensions.

A multi array works like a matrix with various levels, take in example a comparison between one, two, and three Dimensions.

One Dimension is your typical array, it looks like a list of elements.

Dim 1D(3) as Variant

*1D - Visually*
(0)
(1)
(2)

Two Dimensions would look like a Sudoku Grid or an Excel sheet, when initializing the array you would define how many rows and columns the array would have.

Dim 2D(3,3) as Variant
'this would result in a 3x3 grid 

*2D - Visually*
(0,0) (0,1) (0,2)
(1,0) (1,1) (1,2)
(2,0) (2,1) (2,2)

Three Dimensions would start to look like Rubik's Cube, when initializing the array you would define rows and columns and layers/depths the array would have.

Dim 3D(3,3,2) as Variant
'this would result in a 3x3x3 grid

*3D - Visually*
       1st layer                 2nd layer                  3rd layer
         front                     middle                     back
(0,0,0) (0,0,1) (0,0,2) ¦ (1,0,0) (1,0,1) (1,0,2) ¦ (2,0,0) (2,0,1) (2,0,2)
(0,1,0) (0,1,1) (0,1,2) ¦ (1,1,0) (1,1,1) (1,1,2) ¦ (2,1,0) (2,1,1) (2,1,2)
(0,2,0) (0,2,1) (0,2,2) ¦ (1,2,0) (1,2,1) (1,2,2) ¦ (2,2,0) (2,2,1) (2,2,2)

Further dimensions could be thought as the multiplication of the 3D, so a 4D(1,3,3,3) would be two side-by-side 3D arrays.


Two-Dimension Array

Creating

The example below will be a compilation of a list of employees, each employee will have a set of information on the list (First Name, Surname, Address, Email, Phone ...), the example will essentially be storing on the array (employee,information) being the (0,0) is the first employee's first name.

Dim Bosses As Variant
'set bosses as Variant, so we can input any data type we want

Bosses = [{"Jonh","Snow","President";"Ygritte","Wild","Vice-President"}]
'initialise a 2D array directly by filling it with information, the redult wil be a array(1,2) size 2x3 = 6 elements

Dim Employees As Variant
'initialize your Employees array as variant
'initialize and ReDim the Employee array so it is a dynamic array instead of a static one, hence treated differently by the VBA Compiler
ReDim Employees(100, 5)
'declaring an 2D array that can store 100 employees with 6 elements of information each, but starts empty
'the array size is 101 x 6 and contains 606 elements

For employee = 0 To UBound(Employees, 1)
'for each employee/row in the array, UBound for 2D arrays, which will get the last element on the array
'needs two parameters 1st the array you which to check and 2nd the dimension, in this case 1 = employee and 2 = information
    For information_e = 0 To UBound(Employees, 2)
    'for each information element/column in the array
        
        Employees(employee, information_e) = InformationNeeded ' InformationNeeded would be the data to fill the array
        'iterating the full array will allow for direct attribution of information into the element coordinates
    Next
Next

Resizing

Resizing or ReDim Preserve a Multi-Array like the norm for a One-Dimension array would get an error, instead the information needs to be transferred into a Temporary array with the same size as the original plus the number of row/columns to add. In the example below we'll see how to initialize a Temp Array, transfer the information over from the original array, fill the remaining empty elements, and replace the temp array by the original array.

Dim TempEmp As Variant
'initialise your temp array as variant
ReDim TempEmp(UBound(Employees, 1) + 1, UBound(Employees, 2))
'ReDim/Resize Temp array as a 2D array with size UBound(Employees)+1 = (last element in Employees 1st dimension) + 1,
'the 2nd dimension remains the same as the original array. we effectively add 1 row in the Employee array

'transfer
For emp = LBound(Employees, 1) To UBound(Employees, 1)
    For info = LBound(Employees, 2) To UBound(Employees, 2)
        'to transfer Employees into TempEmp we iterate both arrays and fill TempEmp with the corresponding element value in Employees
        TempEmp(emp, info) = Employees(emp, info)
    
    Next
Next

'fill remaining
'after the transfers the Temp array still has unused elements at the end, being that it was increased
'to fill the remaining elements iterate from the last "row" with values to the last row in the array
'in this case the last row in Temp will be the size of the Employees array rows + 1, as the last row of Employees array is already filled in the TempArray

For emp = UBound(Employees, 1) + 1 To UBound(TempEmp, 1)
    For info = LBound(TempEmp, 2) To UBound(TempEmp, 2)
        
        TempEmp(emp, info) = InformationNeeded & "NewRow"
    
    Next
Next

'erase Employees, attribute Temp array to Employees and erase Temp array
Erase Employees
Employees = TempEmp
Erase TempEmp

Changing Element Values

To change/alter the values in a certain element can be done by simply calling the coordinate to change and giving it a new value: Employees(0, 0) = "NewValue"

Alternatively iterate through the coordinates use conditions to match values corresponding to the parameters needed:

For emp = 0 To UBound(Employees)
    If Employees(emp, 0) = "Gloria" And Employees(emp, 1) = "Stephan" Then
    'if value found
        Employees(emp, 1) = "Married, Last Name Change"
        Exit For
        'don't iterate through a full array unless necessary
    End If
Next

Reading

Accessing the elements in the array can be done with a Nested Loop (iterating every element), Loop and Coordinate (iterate Rows and accessing columns directly), or accessing directly with both coordinates.

'nested loop, will iterate through all elements
For emp = LBound(Employees, 1) To UBound(Employees, 1)
    For info = LBound(Employees, 2) To UBound(Employees, 2)
        Debug.Print Employees(emp, info)
    Next
Next

'loop and coordinate, iteration through all rows and in each row accessing all columns directly
For emp = LBound(Employees, 1) To UBound(Employees, 1)
    Debug.Print Employees(emp, 0)
    Debug.Print Employees(emp, 1)
    Debug.Print Employees(emp, 2)
    Debug.Print Employees(emp, 3)
    Debug.Print Employees(emp, 4)
    Debug.Print Employees(emp, 5)
Next

'directly accessing element with coordinates
Debug.Print Employees(5, 5)

Remember, it's always handy to keep an array map when using Multidimensional arrays, they can easily become confusion.


Three-Dimension Array

For the 3D array, we'll use the same premise as the 2D array, with the addition of not only storing the Employee and Information but as well Building they work in.

The 3D array will have the Employees (can be thought of as Rows), the Information (Columns), and Building that can be thought of as different sheets on an excel document, they have the same size between them, but every sheets has a different set of information in its cells/elements. The 3D array will contain n number of 2D arrays.

Creating

A 3D array needs 3 coordinates to be initialized Dim 3Darray(2,5,5) As Variant the first coordinate on the array will be the number of Building/Sheets (different sets of rows and columns), second coordinate will define Rows and third Columns. The Dim above will result in a 3D array with 108 elements (3*6*6), effectively having 3 different sets of 2D arrays.

Dim ThreeDArray As Variant
'initialise your ThreeDArray array as variant
ReDim ThreeDArray(1, 50, 5)
'declaring an 3D array that can store two sets of 51 employees with 6 elements of information each, but starts empty
'the array size is 2 x 51 x 6 and contains 612 elements

For building = 0 To UBound(ThreeDArray, 1)
    'for each building/set in the array
    For employee = 0 To UBound(ThreeDArray, 2)
    'for each employee/row in the array
        For information_e = 0 To UBound(ThreeDArray, 3)
        'for each information element/column in the array
            
            ThreeDArray(building, employee, information_e) = InformationNeeded ' InformationNeeded would be the data to fill the array
        'iterating the full array will allow for direct attribution of information into the element coordinates
        Next
    Next
Next

Resizing

Resizing a 3D array is similar to resizing a 2D, first create a Temporary array with the same size of the original adding one in the coordinate of the parameter to increase, the first coordinate will increase the number of sets in the array, the second and third coordinates will increase the number of Rows or Columns in each set.

The example below increases the number of Rows in each set by one, and fills those recently added elements with new information.

Dim TempEmp As Variant
'initialise your temp array as variant
ReDim TempEmp(UBound(ThreeDArray, 1), UBound(ThreeDArray, 2) + 1, UBound(ThreeDArray, 3))
'ReDim/Resize Temp array as a 3D array with size UBound(ThreeDArray)+1 = (last element in Employees 2nd dimension) + 1,
'the other dimension remains the same as the original array. we effectively add 1 row in the for each set of the 3D array

'transfer
For building = LBound(ThreeDArray, 1) To UBound(ThreeDArray, 1)
    For emp = LBound(ThreeDArray, 2) To UBound(ThreeDArray, 2)
        For info = LBound(ThreeDArray, 3) To UBound(ThreeDArray, 3)
            'to transfer ThreeDArray into TempEmp by iterating all sets in the 3D array and fill TempEmp with the corresponding element value in each set of each row
            TempEmp(building, emp, info) = ThreeDArray(building, emp, info)
        
        Next
    Next
Next

'fill remaining
'to fill the remaining elements we need to iterate from the last "row" with values to the last row in the array in each set, remember that the first empty element is the original array Ubound() plus 1
For building = LBound(TempEmp, 1) To UBound(TempEmp, 1)
    For emp = UBound(ThreeDArray, 2) + 1 To UBound(TempEmp, 2)
        For info = LBound(TempEmp, 3) To UBound(TempEmp, 3)
            
            TempEmp(building, emp, info) = InformationNeeded & "NewRow"
        
        Next
    Next
Next

'erase Employees, attribute Temp array to Employees and erase Temp array
Erase ThreeDArray
ThreeDArray = TempEmp
Erase TempEmp

Changing Element Values and Reading

Reading and changing the elements on the 3D array can be done similarly to the way we do the 2D array, just adjust for the extra level in the loops and coordinates.

Do
' using Do ... While for early exit
    For building = 0 To UBound(ThreeDArray, 1)
        For emp = 0 To UBound(ThreeDArray, 2)
            If ThreeDArray(building, emp, 0) = "Gloria" And ThreeDArray(building, emp, 1) = "Stephan" Then
            'if value found
                ThreeDArray(building, emp, 1) = "Married, Last Name Change"
                Exit Do
                'don't iterate through all the array unless necessary
            End If
        Next
    Next
Loop While False

'nested loop, will iterate through all elements
For building = LBound(ThreeDArray, 1) To UBound(ThreeDArray, 1)
    For emp = LBound(ThreeDArray, 2) To UBound(ThreeDArray, 2)
        For info = LBound(ThreeDArray, 3) To UBound(ThreeDArray, 3)
            Debug.Print ThreeDArray(building, emp, info)
        Next
    Next
Next

'loop and coordinate, will iterate through all set of rows and ask for the row plus the value we choose for the columns
For building = LBound(ThreeDArray, 1) To UBound(ThreeDArray, 1)
    For emp = LBound(ThreeDArray, 2) To UBound(ThreeDArray, 2)
        Debug.Print ThreeDArray(building, emp, 0)
        Debug.Print ThreeDArray(building, emp, 1)
        Debug.Print ThreeDArray(building, emp, 2)
        Debug.Print ThreeDArray(building, emp, 3)
        Debug.Print ThreeDArray(building, emp, 4)
        Debug.Print ThreeDArray(building, emp, 5)
    Next
Next

'directly accessing element with coordinates
Debug.Print Employees(0, 5, 5)