Wrangle Those Names

Excel names are a fine way to store and reference data in a workbook.  Naming a cell allows you to include a readable reference to that cell in your formulas and macros.   Just imagine opening a spreadsheet from two years ago and seeing the formula "=$AG$377*(1+Sheet3!$BB$2110)"... not too meaningful until you navigate to the cells in question and see what's in there.  If, instead, you saw "=Balance*(1+Inflation)", you would instantly know what the formula does.

Names can do much more than simply point to a cell.  You can have a name refer to a RANGE of cells, and then act upon each cell in the range, as in: "=SUM(March_Sales)."  Names can also be dynamically-defined - something I talked about in an earlier post.  Dynamic names aren't simply linked to a particular cell, but are evaluated when the workbook is calculated.  For example, a dynamic name might refer to a member of a list, who's position is determined by some other cell's value.

Names can (and sometimes do) get ugly - especially when they refer to cells that have been deleted.  In this case, you end up with a name that evaluates to an Error reference instead of a value.  Tracking down these errors can be very difficult, because Excel's name management controls are, unfortunately, a bit rudimentary.  You need to go to the Insert menu, choose Name, and then Define.  Then click on each name in the list to verify what it's reference is.  On massive models that have evolved over time, with thousand of defined names, it can be a multi-day task to clean these up.

Another major maintenance headache is tracking down cell formulas that refer to cells in other workbooks.  Sometimes, when you copy from one workbook to another, you don't get the data you want but rather some indirect reference to it's original source.  This is occasionally desirable, but in my experience it is usually a hassle that confounds users, causes unwanted popup dialogs, and burns programming time.

To better deal with these issues, I created the Name Wrangler.

Name wrangler is a simple macro that lists and cleans up names in my workbooks, and identifies all external references in formulas.  The code resides in my Personal macro workbook, and I can invoke it on the active workbook when it's time to clean it up.

The Name Wrangler inserts a blank worksheet in your workbook and generates two tables: all the defined names found, and all formulas that refer to external files.  Names that evaluate to errors are then flagged and deleted.  I use this all the time, and it has saved me a lot of wasted hours scanning through workbooks, tracking down annoying errors and references I don't want.  The first thing I do when a client sends me a large model is run the Name Wrangler to get a handle on what I'm dealing with.

I have packaged the Name Wrangler in a workbook, which you may download here.  Feel free to use this code any way you like.  I welcome your suggestions and comments.

Dynamic Names

One of Excel's most powerful features is the ability to define Names. A Name can refer to a single cell, a range, or a calculated value. You can even define a dynamic Name that refers to a changing range of cells.

You might need to refer to a list of items in your code, but you don't know how big the list will get or where someone might move it. To automatically sync the named range to the data, define a dynamic Name using the Insert -> Name -> Define menu, and this dialog:

The Refers To: field contains a couple of formulae instead of a cell reference, rephrased:
=OFFSET($B$2,1,0,COUNTA($B$2:$B$1000)-1,1)

The Offset formula defines a corner cell, how many rows away, columns away, how many rows to include, and columns to include.  

For the corner cell use the table header, not the first data item, because somebody might delete that cell. The CountA function in the How Many Rows parameter counts non-blank cells in the column.  The heading cell is included in the count, so subtract 1 from it's result to give the actual number of rows in the range.  This example sets an arbitrary limit of 998 items - your knowledge of the likely dataset and any use of the worksheet below the data table are factors in specifying this value.

Blank rows within the data would be a problem, so if that's a possibility, you can nest a few more functions to detect the range of cells you want... but it does get messy and there's no function help when editing names in the dialog, so be warned.

Anyway, now you can use that Named Range in code...

Dim rng as range
For Each rng in Range("Customer_List")
... some code
Next

And you're not putting any actual cell addresses in there so the code stays clean and safe.

An important factor when defining a Name this way is that your Reference formula needs to be safeguarded against possible edits to the worksheet. If a user deletes a cell which is part of the Name's RefersTo property, that Name could break, resolving to a #REF error for ever more. Good Excel programmers anticipate this possibility and set up Names (and Formula references) for maximum durability, helping workbooks live longer.