Yesterday I saw a tweet from @JanWillemTulp,
Happy Holidays! https://t.co/iAnKXJq20a Generate your own data snowflake based on your seasonal greeting! pic.twitter.com/RHi5bLBqSF
— @JanWillemTulp@vis.social /@jwtulp.bsky.social (@JanWillemTulp) December 21, 2015
That got me thinking…? Why can’t we make a snow flake pattern in Excel?
This is what I came up with.
Download Excel Snow Flake Maker
Click here to download the Excel workbook. Press F9 to make another pattern. You can also make pentagonal snow flakes. They are very rare, so go easy on them 🙂
Snow flakes in Excel? How…
I am a little too lazy to explain the calculations behind this. But here is the gist. Examine the calc tab in download workbook for more.
- Let’s assume we have regular hexagon with unit radius (r = 1)
- We calculate the vertices of a regular hexagon (x=sin θ & y = cos θ, where θ = {60,120,180…360})
- Then we rotate the hexagon by random degrees (between 3 to 21) on both sides, shrink r by an arbitrary fraction (20% to 80%) and calculate new vertices. Say these are (x1,y1), (x3,y3)
- We also calculate the vertices of original hexagon when r is multiplied by a random number (between 1 and 3). Say this is (x2,y2)
- Now we have 3 points for each vertex of the hexagon
- (x1,y1) – original hexagon rotated by random degrees to right and shrunk
- (x3,y3) – original hexagon rotated by same random degrees to left and shrunk
- (x2,y2) – original hexagon expanded by a random factor
- We then draw a line connecting the origin (0,0) to (x1,y1) to (x2,y2) to (x3,y3) and back to origin – (0,0)
- We repeat this process for all vertices
- We now have a teeny tiny snow flake.
- When you repeat steps 3 to 7 few more times and overlay all these shapes one on top, we get a nice looking snow flake.
The logic is similar for pentagonal snow flakes. We just use different θs in step 2
Enjoy your snow flake, or the real snow if you live in a colder country. Alas, in Vizag, this winter has been a mild summer. So I am going to imagine snow while lounging under fan with a book in my hands.
Happy holidays.
PS: For more visualization fun this holidays, check out Madelbrot fractals in Excel, 3D Dancing pendulums and Excel fire works.
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...