Journals for



Starting on my next geodata blog post. This is another foundational topic — how to actually get geographic data into a format you can use in your application. I'll cover shapefiles, KML, US census data, OpenStreetMap, and more.


  • Why you should go after a market with strong demand — Some things to consider when looking to start a new product
  • Creatively Misusing TLA+ by Hillel Wayne. This quote stuck out:
  • TLA+ does worst-case model checking, so it fails if it finds any path to an error. This opens a famous trick: if you want to find the set of steps that solve a problem, write a property saying “the problem isn’t solved” and make that an invariant. Then any behavior that finds the solution also breaks the invariant, and the model checker will dutifully spit out the set of steps in that behavior.
  • A bit of math trivia from John D Cook's Blog
  • If a three-digit number is divisible by 37, it remains divisible by 37 if you rotate its digits. For example, 148 is divisible by 37, and so are 814 and 481.

Thanks for reading! If you have any questions or comments, please send me a note on Twitter.