Please Note: This article is written for users of the following Microsoft Excel versions: 2007, 2010, 2013, and 2016. If you are using an earlier version (Excel 2003 or earlier), this tip may not work for you. For a version of this tip written specifically for earlier versions of Excel, click here: Playing with a Full Deck.
Excel is great at generating random numbers, but it is less great at filling a range of cells with random numbers in which no particular number is repeated twice. For instance, you might want to populate 52 cells with the numbers 1 through 52, in random order. (This is very similar to choosing cards from a deck in random order, where a particular card can only be chosen once. Thus the title for this tip.)
There obviously is no built-in Excel function to provide this capability, so you are left to work with macros. Fortunately, such a macro is not terribly difficult to create. The following macro will do the trick nicely:
Please Note:
This article is written for users of the following Microsoft Excel versions: 2007, 2010, 2013, and 2016. If you are using an earlier version (Excel 2003 or earlier), this tip may not work for you. For a version of this tip written specifically for earlier versions of Excel, click here: 
Sub FillRand()
Dim nums() As Integer
Dim maxval As Integer
Dim nrows As Integer, ncols As Integer
Dim j As Integer, k As Integer
Dim Ptr As Integer
Randomize
Set s = Selection
maxval = s.Cells.Count
nrows = s.Rows.Count
ncols = s.Columns.Count
ReDim nums(maxval, 2)
'Fill the initial array
For j = 1 To maxval
nums(j, 1) = j
nums(j, 2) = Int((Rnd * maxval) + 1)
Next j
'Sort the array based on the random numbers
For j = 1 To maxval - 1
Ptr = j
For k = j + 1 To maxval
If nums(Ptr, 2) > nums(k, 2) Then Ptr = k
Next k
If Ptr <> j Then
k = nums(Ptr, 1)
nums(Ptr, 1) = nums(j, 1)
nums(j, 1) = k
k = nums(Ptr, 2)
nums(Ptr, 2) = nums(j, 2)
nums(j, 2) = k
End If
Next j
'Fill in the cells
Ptr = 0
For j = 1 To nrows
For k = 1 To ncols
Ptr = Ptr + 1
s.Cells(j, k) = nums(Ptr, 1)
Next k
Next j
End Sub
This macro uses a two-dimensional array (nums) to figure out which numbers to use and the order in which they should be used. Near the beginning of the macro the array is filled with a static number (1 through the number of cells) and a random number between 1 and the number of cells. This second number is then used to sort the array. Once the array is stored, it is a simple matter to place the original numbers in the cells.
By the way, the reason a two-dimensional array is used is because the Rnd function that VBA uses to generate random numbers can return duplicate values. Thus, even through the second dimension of the array can have duplicates in it, when the array is finally sorted, the first dimension will not have duplicates.
To use the macro, start by selecting the cells you want to have filled with sequential values in a random order. When you run the macro, that range is filled. For instance, if you select ten cells and then run the macro, then those cells are filled with the numbers 1 through 10, in random order.
Note:
ExcelTips is your source for cost-effective Microsoft Excel training. This tip (8269) applies to Microsoft Excel 2007, 2010, 2013, and 2016. You can find a version of this tip for the older menu interface of Excel here: Playing with a Full Deck.
Excel Smarts for Beginners! Featuring the friendly and trusted For Dummies style, this popular guide shows beginners how to get up and running with Excel while also helping more experienced users get comfortable with the newest features. Check out Excel 2013 For Dummies today!
Using the AutoFill feature of Excel is very handy. If you want to expand the utility offered by the feature, all you need ...
Discover MoreNeed to enter a check mark into a cell? There are a number of ways you can get the desired character, depending on the ...
Discover MoreFew things are as frustrating as trying to delete rows or columns and having Excel tell you that you can't perform the ...
Discover MoreFREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."
2017-12-10 20:21:00
Darren E
Thumbs Up, Willy!!
2017-12-08 11:12:01
Willy Vanhaelen
Indeed Rick's solution is a gem as usual. He claims his macro will be much faster than Alan's but didn't test it. I did and it is about 50 times faster !!! But while testing, I discovered his macro has a minor limitation: it has a limit of 65537 cells :-)
Further investigation revealed that TRANSPOSE is responsible for that. So I tried to produce the Num array only with ROW and it worked though the array is now two dimensional. I further took UBound(Nums) out of the loop because it doesn't change during the execution of the macro anyway. This makes the code in the loop a little bit simpler. Here is the result:
Sub FillRand()
Dim X As Long, RandIndex As Long, Nums As Variant, Cell As Range
Randomize
Nums = Evaluate("ROW(1:" & Selection.Count & ")")
X = UBound(Nums)
For Each Cell In Selection
RandIndex = Int(X * Rnd + 1)
Cell.Value = Nums(RandIndex, 1)
Nums(RandIndex, 1) = Nums(X, 1)
X = X - 1
Next Cell
End Sub
I did a test in Excel 2007 for a whole column and it took only 16 seconds to process the more than a million cells.
2017-12-05 23:16:20
Darren E
That is a really clever algorithm Rick Rothstein!
2016-01-09 10:56:53
Rick Rothstein
I don't know if Thomas or Bryan will still be following replies to this blog article or not, but I believe the following macro (which I just posted to Allen Wyatt's other blog article referenced in the "Please Note" box at the top of this blog article) will be faster (untested claim) than Allen Wyatt's code no matter what sorting method was used because my code does not use any sorting whatsoever.
Sub FillRand()
Dim X As Long, RandIndex As Long, Nums As Variant, Cell As Range
Randomize
Nums = Evaluate("TRANSPOSE(ROW(1:" & Selection.Count & "))")
For Each Cell In Selection
RandIndex = Int((UBound(Nums) - X) * Rnd + 1)
Cell.Value = Nums(RandIndex)
Nums(RandIndex) = Nums(UBound(Nums) - X)
X = X + 1
Next
End Sub
Note: This macro will work in XL2003 or later for sure... it may work in earlier versions as well, but XL2003 is the earliest version I own, so I cannot be sure about earlier versions.
2013-09-30 10:01:31
Bryan
Thomas, Allen's solution is actually relatively simple and it's the exact same principal as yours; the difference is the internal Excel sorting method is faster than Allen's. This makes me sad, because his method is more "proper"; I'm guessing, however, that with a more advanced sorting algorithm you could get the times to approach each other.
CPearson has a method that is even faster than using the worksheet to sort (http://www.cpearson.com/excel/SortingArrays.aspx) I tested all 4 methods and here are the results I got with 7,700 values to sort:
Allen Sort: 30.4057
Wrksht Sort: 0.3405
CPrson Sort: 0.1668
With something more reasonable (52, since we are talking cards), the time difference is negligible:
Allen Sort: 0.0015
Wrksht Sort: 0.0738
CPrson Sort: 0.0005
This time the worksheet sorting solution is actually the slowest!
2013-09-28 14:52:43
The proposed method works OK but I think that it is rather complicated.
A simpler and much faster way is to insert two new columns in A and B and fill the first new column A, with a sequence of numbers from 1 to the number of cells in the selection, place next to it, that is the second inserted column B the formula =rand() and fill it down.
Then sort the two new columns having B as key and cutting the sorted A column, to slices equal to the number of rows of the selection and moving them to the selection.
A trial with some 550 rows and 14 columns, run on my PC approximately seven times faster.
If anybody is interested in this version I will be pleased to provide it
Got a version of Excel that uses the ribbon interface (Excel 2007 or later)? This site is for you! If you use an earlier version of Excel, visit our ExcelTips site focusing on the menu interface.
FREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."
Copyright © 2018 Sharon Parq Associates, Inc.
Comments