If IFERROR() were to be a person, I would hug her so hard that Jo (my wife) would get in to a cat fight with her. I know many a woman (and man) who get in to a fight with Excel formulas often. But thankfully, we avoid that as IFERROR is not a real person. It is, however a darned useful formula.
Since I cannot hug a formula anymore than I can get my son to sit tight, I will go ahead and sing an ode to her, in my style – by writing about how useful and powerful IFERROR formula is.
What is IFERROR() Formula & How does it work?
Introduced since Excel 2007, IFERROR() formula checks a formula (or expression) and returns the value of formula if there is no error, otherwise a custom formula.
For eg:
=IFERROR(1/0,"Try splitting an atom instead!")
will give the message Try splitting an atom instead! because the expression 1/0 returns an error (DIV/0 error)
Where as,
=IFERROR(0/1,"Try splitting an atom instead!")
will give the value 0 since 0 divided by 1 is 0.
How does IFERROR help me?
Archimedes once said, “Give me enough data and a spreadsheet, I can make any formula return an error.”
May be he was too confident, but errors are everywhere. And that is why IFERROR is useful. It provides an elegant and simple way to tackle the errors in your workbook.
Several common uses of IFERROR are,
- 1. While writing lookup formulas like VLOOKUP, INDEX+MATCH it is common to search for values that do not exist in your data. You can wrap such formulas in IFERROR for peace of mind.
Ex:=IFERROR(VLOOKUP(...),"Not found") - 2. While using reference formulas like INDEX, OFFSET, frequently, we try to fetch the data that is not in the list of values. This returns #REF errors. You can fix them with IFERROR easily.
Ex:=IFERROR(INDEX(...),"") - 3. While using arithmetic, numeric expressions, usually we end up dividing by 0. You can fix such things by using IFERROR.
Ex:=IFERROR(AVERAGE(...),"0")— Returns 0 when the list has zero values.
Things to keep in mind while IFERRORing:
Please note that IFERROR is oblivious to the type of error. That means, no matter what the error is (DIV/0, #NAME, #N/A, #REF… etc.), IFERROR treats all of them equally and shows the same value. In other words, IFERROR is like “Catch all” in programming world.
How to handle errors if you are using Excel 2003 or below?
In earlier versions of Excel, we have a formula called as ISERROR() that can check an expression or formula for error and return TRUE if so. This formula is not same as IFERROR, but we can use it along with IF() formula to get the same result. For eg.
=IF(ISERROR(VLOOKUP(...)),"Not found",VLOOKUP(...))
works same as, =IFERROR(VLOOKUP(...),"Not found")
Notice that the ISERROR approach evaluates VLOOKUP formula twice!.
Do you IFERROR?
To err is human, to IFERROR is awesome.
Ever since discovering the IFERROR feature in Excel 2007, I have been using it so often. I use it to keep my output sheets clean and my formulas simple.
What about you? Do you use IFERROR? What is your experience like? Would you also give it a hug? If so, would your spouse get in to a cat fight with it? If so can you post some pics of it on our facebook page?
Please share your experiences and tips on using IFERROR() thru comments.
Related awesomeness:
1. How to understand and handle Excel formula errors
2. Excel formulas not working? What to do?
3. Handling errors and 5 other tips for writing better VLOOKUP formulas
8 Responses to “Pivot Tables from large data-sets – 5 examples”
Do you have links to any sites that can provide free, large, test data sets. Both large in diversity and large in total number of rows.
Good question Ron. I suggest checking out kaggle.com, data.world or create your own with randbetween(). You can also get a complex business data-set from Microsoft Power BI website. It is contoso retail data.
Hi Chandoo,
I work with large data sets all the time (80-200MB files with 100Ks of rows and 20-40 columns) and I've taken a few steps to reduce the size (20-60MB) so they can better shared and work more quickly. These steps include: creating custom calculations in the pivot instead of having additional data columns, deleting the data tab and saving as an xlsb. I've even tried indexmatch instead of vlookup--although I'm not sure that saved much. Are there any other tricks to further reduce the file size? thanks, Steve
Hi Steve,
Good tips on how to reduce the file size and / or process time. Another thing I would definitely try is to use Data Model to load the data rather than keep it in the file. You would be,
1. connect to source data file thru Power Query
2. filter away any columns / rows that are not needed
3. load the data to model
4. make pivots from it
This would reduce the file size while providing all the answers you need.
Give it a try. See this video for some help - https://www.youtube.com/watch?v=5u7bpysO3FQ
Normally when Excel processes data it utilizes all four cores on a processor. Is it true that Excel reduces to only using two cores When calculating tables? Same issue if there were two cores present, it would reduce to one in a table?
I ask because, I have personally noticed when i use tables the data is much slower than if I would have filtered it. I like tables for obvious reasons when working with datasets. Is this true.
John:
I don't know if it is true that Excel Table processing only uses 2 threads/cores, but it is entirely possible. The program has to be enabled to handle multiple parallel threads. Excel Lists/Tables were added long ago, at a time when 2 processes was a reasonable upper limit. And, it could be that there simply is no way to program table processing to use more than 2 threads at a time...
When I've got a large data set, I will set my Excel priority to High thru Task Manager to allow it to use more available processing. Never use RealTime priority or you're completely locked up until Excel finishes.
That is a good tip Jen...