Microsoft KB Archive/213818

= XL2000: How to Use a Visual Basic Macro to Sort Arrays in Excel =

Article ID: 213818

Article Last Modified on 11/23/2006

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APPLIES TO


 * Microsoft Excel 2000 Standard Edition

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This article was previously published under Q213818





SUMMARY
In Microsoft Excel 2000, there is no direct method for sorting an array of values with a Microsoft Visual Basic for Applications macro or procedure. This article discusses two different algorithms that you can use to sort arrays: the Selection Sort and the Bubble Sort.



MORE INFORMATION
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Method 1: Selection Sort
Although a Selection Sort is among the easier of sorts to program, it tends to run more slowly than the Bubble Sort on large arrays of data.

To perform a Selection Sort of an array with between 1 to n number of elements, locate the largest element from 1 to n. If this is not element n, exchange the largest element with element n. Then, locate the largest element from 1 to n-1 and, if this is not element n-1, exchange the largest element with element n-1. Next, locate the largest element from 1 to n-2 and, if this is not element n-2, exchange the largest element with element n-2, and so on.

The following is an example of a Selection Sort with a Visual Basic Variant type array.   Type or paste the following in a module sheet: Option Base 1 Function SelectionSort(TempArray As Variant) Dim MaxVal As Variant Dim MaxIndex As Integer Dim i, j As Integer

' Step through the elements in the array starting with the ' last element in the array. For i = UBound(TempArray) To 1 Step -1

' Set MaxVal to the element in the array and save the ' index of this element as MaxIndex. MaxVal = TempArray(i) MaxIndex = i

' Loop through the remaining elements to see if any is       ' larger than MaxVal. If it is then set this element ' to be the new MaxVal. For j = 1 To i           If TempArray(j) > MaxVal Then MaxVal = TempArray(j) MaxIndex = j           End If        Next j

' If the index of the largest element is not i, then ' exchange this element with element i.       If MaxIndex < i Then TempArray(MaxIndex) = TempArray(i) TempArray(i) = MaxVal End If   Next i

End Function

Sub SelectionSortMyArray Dim TheArray As Variant

' Create the array. TheArray = Array(15, 8, 11, 7, 33, 4, 46, 19, 20, 27, 43, 25, 36)

' Sort the Array and display the values in order. SelectionSort TheArray For i = 1 To UBound(TheArray) MsgBox TheArray(i) Next i

End Sub  To run the macro, click the Tools menu, point to Macro, and then click Macros. Select the SelectionSortMyArray macro, and then click Run.

Method 2: Bubble Sort
A Bubble Sort is more difficult to program than the Selection Sort, but it tends to run faster and more efficiently with larger arrays of data.

To perform a Bubble Sort, evaluate 1 to n-1 elements in the array where you compare each element with the one after it (in other words, element 1 is compared to element 2, element 2 is compared to element 3, and so on). If an element is larger than the element after it, those two elements are exchanged. Continue this process until there are no more exchanges of elements. The following is an example of a Bubble Sort with a Visual Basic Variant type array.   Type or paste the following code in a module sheet: Option Base 1 Function BubbleSort(TempArray As Variant) Dim Temp As Variant Dim i As Integer Dim NoExchanges As Integer

' Loop until no more "exchanges" are made. Do       NoExchanges = True

' Loop through each element in the array. For i = 1 To UBound(TempArray) - 1

' If the element is greater than the element ' following it, exchange the two elements. If TempArray(i) > TempArray(i + 1) Then NoExchanges = False Temp = TempArray(i) TempArray(i) = TempArray(i + 1) TempArray(i + 1) = Temp End If       Next i    Loop While Not (NoExchanges)

End Function

Sub BubbleSortMyArray Dim TheArray As Variant

' Create the array. TheArray = Array(15, 8, 11, 7, 33, 4, 46, 19, 20, 27, 43, 25, 36)

' Sort the Array and display the values in order. BubbleSort TheArray For i = 1 To UBound(TheArray) MsgBox TheArray(i) Next i End Sub  To run the macro, click the Tools menu, point to Macro, and then click Macros.</li> Select the SelectionSortMyArray macro, and then click Run.</li></ol>

NOTE: Both of these examples sort in ascending order. To perform a Selection Sort in descending order, change ">" to "<" in the following line of the SelectionSort function: If TempArray(j) > MaxVal Then To perform a Bubble Sort in descending order, change ">" to a "<" in the following line of the BubbleSort function: If TempArray(i) > TempArray(i + 1) Then

Additional query words: XL2000

Keywords: kbdtacode kbhowto kbinfo kbprogramming KB213818

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