Beat Repeat & Open Turntables – August 23rd, 2012

This past Thursday, I had an hour long DJ set at the San Francisco DJ Group’s weekly ‘Beat Repeat & Open Turntables’ event at Raven Bar in SoMa.  You can find a recording of the set below — its missing the first 5 minutes or so, but otherwise is all there.  A tracklisting can be found below the jump.

Continue reading “Beat Repeat & Open Turntables – August 23rd, 2012”

Come Work at TrialPay!

This past Wednesday to Friday, we had our quarterly hackathon at TrialPay.  The hackathon gives engineers and other interested parties a chance to work on some fun projects that aren’t what is normally considered high urgency (e.g., data visualization or in-office announcements) in a short amount of time. 

The hackathon this quarter was hiring theme (i.e., projects that would be useful when trying to recruit new hires).  I used the hackathon as an excuse to write a hiring tune for TrialPay, “Come Work at TrialPay!”  In the future, it would be really fun to make a higher quality recording of the song, and film an accompanying video.  In the meantime, here’s a rough (both in terms of equipment and performance quality) recording 1.

Come Work at TrialPay!

Lyrics below the jump.

Continue reading “Come Work at TrialPay!”


  1. I recorded this using a MacBook Air and an Akai LPK-25 over the course of 30 minutes in an office phone room.

Photo Hack Day 3

This past weekend, me and my co-worker Chris Chen participated in Photo Hack Day 3, a hackathon sponsored by FaceBook in the Dropbox HQ.  The hackathon gave participants a chance to build photo-oriented programs using a variety of APIs and tools.  Chris and I built a pretty simple Facebook app 1, since we wanted to learn how to use the Facebook API.  Our as-of-yet untitled project can be found at the following link:

Chris and Dave’s Photo Hack Day 3 Project

The app scrapes your most recent facebook photos, and ranks and resizes them based on popularity (a metric that we defined — simply the sum of the number of likes and comments the photo has).  We didn’t have time to finish the project, but the next step would be to cleverly re-arrange the re-sized photos into some aesthetically pleasing collage.  For now, they just get dumped in a list.


  1. Neither of us are software engineers, although we both have some amount of programming experience


Every year in the JHU Physics and Astronomy Department, the first year graduate students play an April Fool’s Day prank.  The prank usually comes by way of embellishing the department lobby 1

Our first year class chose the somewhat topical “#occupybloomberg” as our April Fool’s Day Prank, transforming the Bloomberg lobby into an occupy encampment.  Strewn about the lobby were cardboard signs, filled with occupy-like physics puns.  The centerpiece of the entire prank was a giant picture of our most-beloved quantum mechanics lecturer, Zlatko Tesanovic, and one of his many quote’s insinuating that physicists are entirely to blame for the economic recession:

“Physicists have played a great part in the economic collapse of the planet.”

Below are some pictures of #occupybloomberg.  Enjoy!


  1. In past years, this has included the construction of a circus scene, but also covering the entire lobby with slighly-filled cups.


A recent project of mine has been the development of a small python program called Tunesquare. Tunesquare creates an aural representation of a foursquare user’s entire check-in history. I was motivated to start this project while searching the web for a good check-in visualization tool. After WeePlaces stopped supporting foursquare check-ins, I was looking for a good website to view my foursquare check-ins on a map 1. It occurred to me that while tons of apps built around the foursquare API visualize a user’s check-in history, no one had attempted to create a non-visual representation of the data. Tunesquare does just that. Given a user’s check-in history, the program creates a sequence of MIDI notes whose length and pitch are determined by the latitude and longitude of the user’s check-ins 2. For interested parties, a rough version of the program is included below (along with a few notes for myself).

Tunesquare 0.1
Developed by Dave Holtz
Dependencies: numpy, Foursquare (A python wrapper for the Foursquare API), tkSnack
Things that need to be done:
– Envelope the sine wave to eliminate clipping.
– Fine-tune the use of the longitude and latitude for better musicality.
– Integrate into a web interface.
– Add map visualization (possibly with Google Maps).

While the application will eventually live within a web interface, for now you can still download it and run it from the command line. Here’s a brief tutorial of how to do that. Continue reading “Tunesquare”


  1. Incidentally, 4sqmap is great for this.
  2. Tunesquare goes through the notes sequentially, with each note corresponding to one check-in.