Sharla Gelfand



A few weeks ago I went to rstudio::conf() and came home sans wallet, sans keys, but plus a lot of inspiration to actually work on personal projects and try out some of the new (and not-so-new!) things that RStudio has to offer. I’d touched Shiny a few times but honestly maybe hadn’t used RMarkdown since the Sweave days. Combine this with listening religiously to Not So Standard Deviations and getting the brilliant idea from Hilary to do my personal finances in R, and I had a project!

I find my finances to be awkward and hard to coordinate. Previously I used a mix of Mint.and, for a while, a spreadsheet that looked something like this:

(what did I do if I had more transactions than the number of provided lines? ¯\(ツ)/¯)

but neither were really ideal! Mint isn’t designed for the way Canadian bank accounts work (or maybe I don’t have adult enough banking for how Mint works), but I’d been finding it really hard to keep track of my spending, and especially my savings… without it looking like I was spending that money instead of saving it.


Peppermint is a hilariously named personal finance app that reads from a bunch of google sheets and creates summaries + visualizations based on what I wanted to see most:

  • the current month’s spending, in categories ($ amount, as well as % of my income), and compared to a set budget
  • itemized list of the current month’s spending
  • spending over time
  • the current month’s savings, based on a set goal
  • savings over time

You can go into the app and click around (there’s a tab!), and all of the code is available on github.

Since personal finance is personal: I’ve gone to some efforts to anonymize the data – pretty much everything is multiplied by a random number between 0.1 and 5, and all descriptions for my transactions (i.e., where I shop) are replaced with random strings. The categories are unchanged, but some runs it’ll look like I spend 0.4% of my monthly income on $3,000 worth of rent and aim to save $200. So yes, the numbers you see up there are a lie! My car insurance is overpriced, but not $1,200 a month overpriced.

Initially I was manually exporting my transaction data from Mint but knew that wouldn’t last - I did look into a Python API that seemed pretty good (in theory) but figuring out cookies and credentials to get from Chrome was beyond the scope of my MVP (aaand I didn’t want to write Python).

So now, everything is in a bunch of google sheets that I update manually - I think this is good for me. It helps me actually look at what I’m spending 💰 on, and especially cash transactions, which… if you see the personal version of my app, you’ll see I have no idea what I spend that cash on at all. Feeling optimized, and at least there’s no more of this:

ps: I would be remiss if I didn’t shout out Kathyrn Morrison, who also picked up Hilary’s idea and did a great post on managing her personal finances in R!

Some things I learned along the way:

  • Shiny vs shinydashboard vs flexdashboard – yeah, I wasn’t too sure either! I found this StackOverflow post which is a great explanation of the difference, and eventually settled on flexdashboard for this project, primarly because I didn’t need a ton of/any interactivity. Future iterations TBD.
  • Sys.time() is timezone dependent (of course), and the timezone that is on is not necessarily my timezone – which results in a small window where no data was showing up for the current month because, for me, the current month was January, but in Shiny world, it was February.
  • How to write my first github issue!
  • If you call Universal Studios enough times (i.e., until they have actually found your wallet), they will mail you your wallet!

pps: this is my first blog post! some notes on that:

  • Yihui Xie’s blogdown package is really, really cool. It’s still in beta without a ton of documentation, and I couldn’t quite figure it out (though Amber Thomas’s post on it is amazing, but I’m looking forward to trying it out again in the future!
  • This blog is created using Jekyll. There are a ton of guides to setting up a new site, but I ended up using a process similar to the one outlined here by forking and changing an existing theme.