Matt Maenner asked about the sawtooth pattern in the figure in my last post on Chutes & Ladders. Damn you, Matt! I thought I was done with this. Don’t feed my obsession. My response was that if the game ends early, it’s even more likely that it’ll be the kid who went first who won. […]
I was playing Chutes & Ladders with my four-year-old daughter yesterday, and I thought, “How long is this going to take?” I saw an interesting mathematical analysis of the game a few years ago, but it seems to be offline, though you can read it via the wayback machine. But that didn’t answer my specific […]
Stack Exchange is a series of question-and-answer sites, including Stack Overflow for programming and Cross Validated for statistics. I was introduced to these sites at a short talk by Barry Rowlingson at the 2011 UseR! meeting, “Why R-help must die!“ These sites have a lot of advantages over R-help: The format is easier to read, […]
If you’re not using version control, you should be. Learn git. If you’re not on github, you should be. That’s real open source. To help some colleagues get started with git and github, I wrote a minimal tutorial. There are lots of git and github resources available, but I thought I’d give just the bare […]
There was lots of discussion on twitter yesterday about Graham Coop’s paper with Peter Ralph (or vice versa), on The geography of recent genetic ancestry across Europe, particularly regarding the FAQ they’d created. I was eager to take a look, and, it’s slightly embarrassing to say, I first did a search to see if they’d […]
It’s great that, in a step towards improved reproducibility, the Nature journals are removing page limits on Methods sections: To allow authors to describe their experimental designs and methods in enough detail for others to interpret and replicate them, the participating journals are removing length restrictions on Methods sections. But couldn’t they include the Methods […]
When physicists do mathematics, they don’t say they’re doing “number science”. They’re doing math. If you’re analyzing data, you’re doing statistics. You can call it data science or informatics or analytics or whatever, but it’s still statistics. If you say that one kind of data analysis is statistics and another kind is not, you’re not […]
Another R tip: beware of as.character applied to a list. Really, beware of grep with a list: You might have thought that the result would be just 1, but grep expects a vector of character strings. If the input is not that, it uses as.character(). Since the result of that starts with "c(", grep finds […]
It’s widely understood that, in R programming, one should avoid for loops and always try to use apply-type functions. But this isn’t entirely true. It may have been true for Splus, back in the day: As I recall, that had to do with the entire environment from each iteration being retained in memory. Here’s a […]
![x[[c(5,3)]]](http://feeds.wordpress.com/1.0/comments/kbroman.wordpress.com/1600/)
An R tip: Did you know that x[[c(5,3)]] is the same as x[[5]][[3]]? I should make more thorough use of this. In the help file for [[: [[ can be applied recursively to lists, so that if the single index i is a vector of length p, alist[[i]] is equivalent to alist[[i1]]...[[ip]] providing all but […]
