Removing duplicate data is like morning coffee for us, data analysts. Our day must start with it.
It is no wonder that I have written extensively about it (here: 1, 2, 3, 4, 5, 6, 7, 8).
But today I want to show you a technique I have been using to dynamically extract and sort all unique items from a last list of values using Pivot Tables & OFFSET formula.
This is how it goes…,
Step 1: Select your data & Create a pivot table
Just select any cell and insert a pivot table. Very simple right?
Step 2: Drag the field(s) to row label area of pivot
Like this.
Make sure you have turned off grand totals and sub-totals as we just need the names. And sort the pivot table.
Step 3: Create a named range that refers to the pivot table values
Using OFFSET formula, we can create a named range that refers to pivot table values and grows or shrinks as the pivot is refreshed. Assuming the pivot table row values start in cell F6, write a formula like,
=OFFSET($F$6, 0,0,COUNTA($F:$F)-1,1) and map it to a name like lstProducts.
The formula gives us all the values in column F, starting F6. The COUNTA($F:$F)-1 ensures that we get only row labels and not the title (in this case Product Names).
Step 4: Use the named range in formulas etc. as you see fit
That is all. Nothing else.
Just make sure that you refresh the pivot table whenever source data changes.
Download example file with this technique
Click here to download an example file and play with it to understand how this works.
How do you deal with duplicate data?
In my work, I come across duplicate data all the time. I have been using pivot table based technique with great success. It is fast, reliable and easy to setup. The only glitch is that you need to refresh the pivot tables whenever source data changes. However, you can automate this by writing a simple macro.
What about you? How do you deal with duplicate data? Share your techniques, tips & ideas using comments.
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...