Articles by JD Long

Solving easy problems the hard way

March 17, 2012 | JD Long

There’s a charming little brain teaser that’s going around the Interwebs. It’s got various forms, but they all look something like this: This problem can be solved by pre-school children in 5-10 minutes, by programer – in 1 hour, by people with higher education … well, check it yourself!  8809=6 7111=0 2172=0 6666=4 1111=0 3213=0 7662=2 9313=1 0000=4 2222=0 3333=0 5555=0 8193=3 8096=5 7777=0 9999=4 7756=1 6855=3 9881=5 5531=0 2581=? SPOILER ... [Read more...]

Fitting Distribution X to Data From Distribution Y

May 12, 2011 | JD Long

I had someone ask me about fitting a beta distribution to data drawn from a gamma distribution and how well the distribution would fit. I’m not a “closed form” kinda guy. I’m more of a “numerical simulation” type of fellow. So I whipped up a little R code ... [Read more...]

Shell scripting EC2 for fun and profit

May 6, 2011 | JD Long

Lately I’ve been doing some work with creating ad-hoc clusters of EC2 machines. My ultimate goal is to create a simple way to spin up a cluster of EC2 machines for use with Bryan Lewis’s very cool doRedis backend for the R foreach package. But that’s a ... [Read more...]

Details of two-way sync between two Ubuntu machines

April 18, 2011 | JD Long

In a previous post I discussed my frustrations with trying to get Dropbox or Spideroak to perform BOTH encrypted remote backup and AND fast two way file syncing. This is the detail of how I set up for two machines, both Ubuntu 10.10, to perform two way sync where a file ... [Read more...]

Fast Two Way Sync in Ubuntu!

April 9, 2011 | JD Long

I love the portability of a laptop. I have a 45 min train ride twice a day and I fly a little too, so having my work with me on my laptop is very important. But I hate doing long running analytics on my laptop when I’m in the office ... [Read more...]

Where the heck has JD been?

March 22, 2011 | JD Long

It’s been pointed out to me that I haven’t had any blog posts in a while. It’s true. I’m fairly slack. But in the last few months I’ve changed jobs (same firm, new role), written an R abstraction on top of Hadoop, been to China, ... [Read more...]

Connecting to SQL Server from R using RJDBC

September 22, 2010 | JD Long

A few months ago I switched my laptop from Windows to Ubuntu Linux. I had been connecting to my corporate SQL Server database using RODBC on Windows so I attempted to get ODBC connectivity up and running on Ubuntu. ODBC on Ubuntu turned into an exercise in futility. I spent ... [Read more...]

Even Simpler Multivariate Correlated Simulations

August 31, 2010 | JD Long

So after yesterday’s post on Simple Simulation using Copulas I got a very nice email that basically begged the question, “Dude, why are you making this so hard?” The author pointed out that if what I really want is a Gaussian correlation structure for Gaussian distributions then I could ... [Read more...]

Stochastic Simulation With Copulas in R

August 30, 2010 | JD Long

A friend of mine gave me a call last week and was wondering if I had a little R code that could illustrate how to do a Cholesky decomposition. He ultimately wanted to build a Monte Carlo model with correlated variables. I pointed him to a number of packages that ... [Read more...]

Chicago R Meetup: Healthier than Drinking Alone

May 24, 2010 | JD Long

I’m kinda blown away by the number of folks who have joined the Chicago R User Group (RUG) in the last few weeks. As of this morning we have 65 people signed up for the group and 25 who have said that they are planning on attending the meetup this Thursday (...
[Read more...]

Virtual Conference: R the Language

May 3, 2010 | JD Long

On Tuesday May 4th at 9:30 PM central, 10:30 eastern, I’ll be giving a live online presentation as part of the open conference series. I’ll be speaking about R and why I started using R a couple years ago. This is NOT going to be a technical presentation ...
[Read more...]

Simulating Dart Throws in R

April 16, 2010 | JD Long

Back in November 2009 Wired wrote an article about some grad students who decided to try to stochastically model throwing darts. Because I don’t actually read printed material I didn’t see the article until a couple of months ago. My immediate thought was, “hey, I drink beer. I throw ... [Read more...]

The Future of Math is Statistics

April 9, 2010 | JD Long

The future of math is statistics… and the language of that future is R: I’ve often thought there was way too little “statistical intuition” in the workplace. I think Author Benjamin would agree. [Read more...]

Lookup Performance in R

April 2, 2010 | JD Long

Rumor has it that Joe Adler, author of the O’Reilly Book R in a Nutshell, has joined Linked In as a data scientist.  But that does not keep him from still pumping out some interesting content over at His latest article is about lookup performance in R. ... [Read more...]
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