Identifying Values that Don't Follow a Specific Pattern

Vishwajeet has a series of part numbers in a column. These part numbers must follow a specifc pattern (2 numbers, 5 letters, 4 numbers, 1 letter, 1 number, 1 letter, and 1 number). He wonders if there is a way to easily identify which of the cells in the column vary from this pattern.

There are a number of ways you can approach this task, depending on the true nature of your data. For instance, you could use a formula like this in a helper column:

=AND(LEN(A1)=15,ISNUMBER(--LEFT(A1,2)),ISTEXT(MID(A1,3,5)),
ISNUMBER(--MID(A1,8,4)),ISTEXT(MID(A1,12,1)),ISNUMBER(--
MID(A1,13,1)),ISTEXT(MID(A1,14,1)),ISNUMBER(--RIGHT(A1,1)))

The formula (which is quite long) returns True or False, depending on whether the pattern is correct or not. There is a problem with the formula, however. It won't catch symbols used in place of letters (such as a dollar sign or an asterisk) and it won't catch some symbols used in place of numbers (such as a period or a percent sign). The reason is that the ISTEXT function considers symbols to be text and the ISNUMBER function parses something like "1.23" as a number.

If you want to catch this improper use of symbols, the following formula could be used:

=AND(LEN(A1)=15,ISNUMBER(SUM(SEARCH(MID(A1,{1,2,8,9,10,11,
13,15},1),"0123456789"),SEARCH(MID(A1,{3,4,5,6,7,12,14},1),
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"))))

This one works because it uses the SEARCH function to effectively check every character in the part number. One would think that you might need to enter the formula as an array formula (terminating it with Ctrl+Shift+Enter), but interestingly enough, I get no difference in results when I use it as a regular formula vs. an array formula.

If you need to check the part number patterns quite a bit, you may want to consider using a macro to do the checking. The following is a short user-defined function that uses the Like operator to see if the pattern is followed.

Function CheckPattern(rCell As Range) As Boolean
    Dim sPattern As String

    sPattern = "##[A-Z][A-Z][A-Z][A-Z][A-Z]####[A-Z]#[A-Z]#"

    CheckPattern = rCell.Value Like sPattern
End Function

Note the use of the sPattern variable. This is the pattern to be followed when the Like operator does its comparison. Each occurrence of the # symbol means that any digit can be in this position. Each occurrence of [A-Z] means that the position can be one letter in the range of A to Z.

You can find more about the meaning of the characters you can include in the pattern by visiting this page at one of Microsoft's sites:

https://docs.microsoft.com/en-us/dotnet/visual-basic/language-reference/operators/like-operator

This site is actually for Visual Basic, not VBA, but this particular page of information will work just fine in VBA.

In order to use the CheckPattern user-defined function, you can place the following in any cell in your worksheet:

=CheckPattern(A1)

This assumes that the part number is in cell A1, as do all the other formulas presented in this tip.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (3391) applies to Microsoft Excel 2007, 2010, 2013, and 2016.