This is second part of 2 part series on conditionally formatting dates in excel.
In yesterday’s post we have learned how to conditionally format dates using excel. In this article, you will learn how to use these conditional formatting tricks to highlight repeat customers in a list of sales records.
The problem: Highlighting repeated customers in a list
Let us say you run a small retail store. And you want to give special discounts to all the repeat customers.
Repeat customer is someone who bought at least twice from you in last 30 days. (If the person bought twice but the gap between 2 purchases is more than 30 days they are not repeat customers).
The Data:
Let us assume your sales data has these 2 columns – customer ID and purchase date. I have shown first few rows here. Let us assume the data is in the range B4:C53.
Finding if a customer is repeat – The Formula:
If we just want to highlight without considering the purchase dates,
we can use a simple formula like =COUNTIF($B4:$B53,$B3)>1 in the conditional formatting applied over the range B4:C53.
But we need to consider the date as well,
hmm, now that is tricky !??
May be time for a sip of that coffee. Go take it, I am waiting..,
How about the SUMPRODUCT? We all know that sumproduct formula can be used to test more than one condition.
The formula:
=IF(C4>TODAY()-30,IF(SUMPRODUCT(--($B$4:$B$53=B4),--($C$4:$C$53>(TODAY()-30)))>1,"R","N"),"N")
Now that is one lengthy badass formula. Like Sergeant Martin Riggs. Bad, but still cool.
So what is this formula really doing? It is going to give us “R” if a customer is repeat and “N” if not. See this explanation to understand how it works.
Note: the double dashes “–” make the values as 0s and 1s from a bunch of “trues” “falses”. To know why sumproduct is such a beautiful and robust formula look no further.
The Conditional Formatting
Now that you have figured out the formula to determine a customer is repeat or not, applying conditional formatting is a piece-o-cake.
Just select the range B4:C53, go to conditional formatting and select “formula” option. Now specify the above formula and check if its output is “R” and apply formatting.
I am not telling you how to do this. It is your homework. Go figure!
That is all. Your workbook now highlights repeat customers in the last 30 days. Remember, as you reopen the file a week later, the highlighting logic changes since the date has changed.
Download the example workbook
Click here to download the example workbook and understand how to highlight repeat customers using conditional formatting. The file works in Excel 2003+.
What is your experience?
Share your tips and ideas on using conditional formatting with dates. What are the situations you usually face and how to solve them? I am never too old for this, so please share.
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...