The other day, while I was putting my kids to sleep, this idea came to me. How do I check if a cell contains a palindrome, using Excel formulas?
Next morning, I wrestled with excel for about 20 minutes and boom, the formula is ready.
Here is how it works:
If you enter a word or phrase in column B, it would tell you whether it is a palindrome or not.
But what is a palindrome?
A palindrome is a word, phrase, verse, or sentence that reads the same backward or forward. For example: A man, a plan, a canal, Panama!
[definition from palindromelist.net]
So, to check if a cell contains palindrome, we need to reverse the cell contents and see if both original and reverse are the same.
For example if B1 contains MAN, then the reverse would be NAM and hence MAN is not a palindrome.
But how do we write a formula to check if a cell has palindrome?
- Assuming B1 contains the word (or phrase), the first step is to clean it. That means, we need to remove any spaces, commas, exclamation marks & other punctuation symbols. So a phrase like “Cigar? Toss it in a can. It is so tragic.” would become “CigarTossitinacanItissotragic”.
- The next step is to match this cleaned text (lets say this will be C1) with the reverse of it.
- But there is no reverse formula. So we use MID() to extract one letter at a time and match it with the corresponding letter from end. (ie first letter with last letter, second letter with second last letter etc.)
- To do this, we use,
MID(C1,ROW(OFFSET($A$1,,,LEN(C1))),1=MID(C1,LEN(C1)-ROW(OFFSET($A$1,,,LEN(C1)))+1,1) - The left portion of this formula would give individual letters in C1 in left to right order and the right portion would give same in reverse order.
- We wrap this in a lovely SUMPRODUCT formula so that we can check for palindrome-ness of B1 using
=IF( SUMPRODUCT( ( MID(C1,ROW(OFFSET($A$1,,,LEN(C1))),1) = MID(C1,LEN(C1)-ROW(OFFSET($A$1,,,LEN(C1)))+1,1)) + 0 ) = LEN(C1), "It’s a Palindrome", "Nah!")
How does this formula work?
Well, that is your weekend homework. Go figure.
One more homework if you are game
If you feel like playing with words, here is another challenge.
How would you test if a cell contains alliteration?
(Alliteration here is defined as sentence where all words begin with same letter)
Go ahead and post your answers using comments.
Download Palindrome Test Excel Workbook
Click here to download the excel workbook and see the palindrome test formulas yourself.
Learn more about Excel Array Formulas
Array formulas are a special class of Excel formulas that can provide powerful results with little work. We have a huge collection of array formula examples on chandoo.org. Go thru below list and see how deep the rabit hole goes.
SUMPRODUCT Formula and how to use it
Advanced SUMPRODUCT Queries
Use Array Formulas to check if a list is sorted
Calculating sum of digits in a number using formulas
Check if a number is Prime using array formulas
More… Excel Array Formulas – Examples & Demos
PS: Monday is our (Indian) Independence Day. So I will see you again on Tuesday.
PPS: On Tuesday, we will be announcing our Excel Formula Crash Course. Get ready.
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...