David posts a question about how to solve this knapsack problem using the R statistical computing and analysis platform. My reply in the comments seems to have disappeared for a while so here is my proposed solution:

Premise I was recently asked to verify the coefficients of a linear model fit to sets of data, where each row of the input file was a "site" and each column contained the dependent variable through time (i.e. column 1 = time step 1, column 2 = time step 2, etc.). This format is cumbersome in that it...

I've pushed my slides from the presentation I've given at useR! a few minutes ago here

I'm back from vacation, so I'll post something substantive later today.

I'm back from vacation, so I'll post something substantive later today.

A colleague of mine recently asked about computing basic summary statistics from grouped data in R. These are a couple examples that I suggested. Additional documentation for the plyr package can be found here. read more

The plot in section 7.3 has some problems. At the very least, the jittered values ought to be between 0 and 1, so the smoothed lines ﬁt better with them. Once again we use the data generated in section 7.2 as an example. For both SAS and R, we use conditioning (section 1.11.2) to make the jitter happen...

There's no doubt that by now you've noticed that we're big fans of R around here. It's completely free, has superior graphing capabilities, and with all the extension packages available there isn't much it can't do. One of the problems with R especially to new users is that it isn't obvious how to find help when you...

Just a short note that version 2.9.1 of R was released yesterday. And a corresponding Debian release went out as usual on the same day. One sour note: as the Java toolchain is currently broken, I had to disable compile-time support for Java. Just run R...

Just a short note that version 2.9.1 of R was released yesterday. And a corresponding Debian release went out as usual on the same day. One sour note: as the Java toolchain is currently broken, I had to disable compile-time support for Java. Just run R CMD javareconf once installed if you need it. Speaking of broken, I had...

Our article (by Yu-Sung, Jennifer, Masanao, and myself, and based also on work with Kobi, Grazia, and Peter Messeri) will be appearing in the Journal of Statistical Software, in a special issue on missing-data imputation. Here's the abstract: ...

Something that's very important to be able to do in data analysis and visualization is to filter out cases. Let's say you want to do identical analyses of two different groups, or of one group and then a subset of it. R can do this a little differently; instead of merely filtering out cases you can create an object...