Hello all
Chandoo has graciously, some may say stupidly, given me access to post on Chandoo.org.
I have been a reader of Chandoo.org for about 2 years and have spent most of my time contributing to the Forums where I have just posted my 950th post.
I have written a few small posts which Chandoo has used, and I wrote a major post on Monte Carlo Simulation and Data Tables:
http://chandoo.org/wp/2010/05/06/data-tables-monte-carlo-simulations-in-excel-a-comprehensive-guide/
Which was well recieved.
I will be starting to post about once per week and will be introducing a series of real life problems and how they can be tackled using Excel.
Hiding Error Messages
I like to leave certain error messages in place because they can show you what your data is doing, but they look horrible when you print out reports.
One way around this is to use functions like =Iserr or =Iserror to trap the error and display something else
Eg: A formula =A1/A2 will divide A1 by A2 and give you an answer,
but if A2 is 0 you will get a Divide Zero Error #DIV/0!
To fix that you can use the =IFERROR Function =IFERROR(A1/A2,0) which will now give you a zero if A2 is zero
But if you don’t mind seeing, or want to see, the errors on screen, but don’t want to print them out you can have Excel hide the error messages at Print time.
How:
Goto the Page Setup menu
On the Sheet Tab use the Cell errors as:
and select <Blank>, “–“ or #N/A as appropriate
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...