Imagine having two annoying little bloggers looking over your shoulder and trying to mess up with the chart you are making….
I am still waiting, go ahead, imagine…
Now come back, that is exactly what “The Chart DoctorBusters” is all about. It is a new series of posts on PHD and Jon Peltier where we take badly made charts, one at a time and suggest improvements, alternative visualization options and corrective measures.
For a doctor to be really good, he needs to have really sick people. In our case we need bad charts. I mean really bad ones with all those 23 colors or 17 pies or stressful extra grid lines or .. ok, you get the picture.
Here is what you should do:
- Upload your chart or excel workbook to a public site like skydrive.
- Now go to this google docs form and submit your charts
- (alternatively you can tweet us on @r1c1 or @Jon_Peltier)
Here is what Jon and I will do:
Every week we will take one of the really bad charts and post an entire article dissecting the problems and prescribing the treatment. We will take turns, so one week it will be Peltier and next week it will be me. We will also try to comment on each other’s treatment. With some luck, we should get other leading authorities in charting world to come and comment here.
Some rules to keep in mind:
- We are talking about charts here, not complicated dashboards or vibrating visualizations.
- As much as possible try to post the actual data associated with the chart and tell us clearly what you think the chart was trying to achieve.
- Remember, even parapsychologists get psyched.
- Have fun 🙂
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...