Reference

Vaccination rates by school in Massachusetts

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Here’s an interesting data set.  This table contains vaccination rates for kindergartners by town and school in Massachusetts. It shows immunization rates for DTaP (Diptheria, Tetanus, and Pertussis), Polio, MMR (Measles, Mumps, Rubella), and Hepatitis B. It also lists immunity to chickenpox. It’s published here as an Excel file.  That makes it easier to numbercrunch, … Read more

Google Chromecast digisign references

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These are notes on digital signage on the Google Chromecast. Google’s docs https://cast.google.com/publish/#/overview   Console https://developers.google.com/cast/docs/custom_receiver   Writeup SaaS vendors. https://www.signsimple.com/ (local launch) http://launch.signagely.com/  (not up yet) Chromecast code repos https://github.com/pjjanak/chromecast-hello-world "C" is for Chromecast: hacking digital signage Limitations The Chromecast device does a good job of displaying media at 1080p resolution.  However, any web … Read more

Starting a new web site or blogging project? Read this! Seriously.

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Mr. Ognjen Duraskovic first got in touch with me with an offer to translate my MMWW WordPress plugin to Spanish and Serbian, which of course, I gratefully accepted. Gracias! хвала! It was an extra-cool offer because MMWW contains all kinds of readable text strings for the photographic details embedded in Exif metatdata. He dealt with all … Read more

Fast nearest-location finder for SQL (MySQL, PostgreSQL, SQL Server)

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I’ve spent enough time goofing around with location-finder software that it’s worth writing up how to do it.   Of course, finding distances on the surface of the earth means using Great Circle distances, worked out with the Haversine formula, also called the Spherical Cosine Law formula. The problem is this: Given a table of … Read more

Transcoding JPEG optimizer from Mozilla

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The people at Mozilla have produced a transcoding JPEG optimizer. https://github.com/mozilla/mozjpeg/releases This thing is sweet: it takes ordinary JPEG files and recompresses them much more efficiently without making the images deteriorate. It uses the long-standing and well-tested Independent JPEG Group reference implementation, and adds a bunch of optimizations. It’s not built for GUI users; it’s … Read more

Filling in missing data with sequences of cardinal integers

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When you’re extracting summaries of information from a database, sometimes rows are missing.  For example, if you are keeping track of number of customers by day, you might use a query like this: View the code on Gist. You might get a result set like this: 2014-03-07 122 2014-03-08 355 2014-03-10 234 2014-03-11 119 Notice … Read more

The Vincenty great-circle distance formula

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This Vincenty formula is a more numerically stable version of the spherical cosine law formula (commonly and wrongly known as the Haversine formula) for computing great circle distances. The question of numerical stability comes up specifically when the distances between points are small. In those cases the cosine is very close to 1, so the … Read more