Category: r (Page 6 of 20)

Paying for a job well done

2014-11-26 / Luis

At the moment I am writing R code that involves a lot of simulation for a project. This time I wanted to organize the work properly, put a package together, document it,… the whole shebang. Hadley Wickham has excellent documentation for this process in Advanced R, which works very well as a website. Up to this point there is nothing new; but the material is also available as a book.

At this point in my life I do not want to have a physical object if I can avoid it. On top of that, code tutorials work a lot better as a website, so one can copy, paste and experiment. PDF or ebooks are not very handy for this subject either. Here enters a revolutionary notion: I like to pay people who do a good job and, in the process, make my job easier but sometimes I do not want an object in exchange.

Sometimes I feel (some) need for speed

2014-07-12 / Luis

I’m the first to acknowledge that most of my code could run faster. The truth of the matter is that, in essence, I write ‘quickies’: code that will run once or twice, so there is no incentive to spend days or hours in shaving seconds of a computation. Most analyses of research data fall in to this approach: read data-clean data-fit model-check model-be happy-write article-(perhaps) make data and code available-move on with life.

One of the reasons why my code doesn’t run faster or uses less memory is the trade-off between the cost of my time (very high) compared to the cost of more memory or faster processors (very cheap) and the gains of shaving a few seconds or minutes of computer time, which tend to be fairly little.
Continue reading

Less wordy R

2014-03-12 / Luis

The Swarm Lab presents a nice comparison of R and Python code for a simple (read ‘one could do it in Excel’) problem. The example works, but I was surprised by how wordy the R code was and decided to check if one could easily produce a shorter version.

The beginning is pretty much the same, although I’ll use ggplot2 rather than lattice, because it will be a lot easier (and shorter) to get the desired appearance for the plots:
Continue reading

R as a second language

2014-01-06 / Luis

Imagine that you are studying English as a second language; you learn the basic rules, some vocabulary and start writing sentences. After a little while, it is very likely that you’ll write grammatically correct sentences that no native speaker would use. You’d be following the formalisms but ignoring culture, idioms, slang and patterns of effective use.

R is a language and any newcomers, particularly if they already know another programming language, will struggle at the beginning to get what is beyond the formal grammar and vocabulary. I use R for inquisition: testing ideas, data exploration, visualization; under this setting, the easiest is to perform a task the more likely is one going to do it. It is possible to use several other languages for this but—and I think this is an important but—R’s brevity reduces the time between thinking and implementation, so we can move on and keep on trying new ideas^†.
Continue reading

Gliding in a hierarchy of models (Photo: Luis, click to enlarge).

Teaching linear models

2014-01-02 / Luis

I teach several courses every year and the most difficult to pull off is FORE224/STAT202: regression modeling.

The academic promotion application form in my university includes a section on one’s ‘teaching philosophy’. I struggle with that part because I suspect I lack anything as grandiose as a philosophy when teaching: as most university lecturers I never studied teaching, although I try to do my best. If anything, I can say that I enjoy teaching and helping students to ‘get it’ and that I want to instill a sense of ‘statistics is fun’ in them. I spend quite a bit of time looking for memorable examples, linking to stats in the news (statschat and listening the news while walking my dog are very helpful here) and collecting data. But a philosophy? Don’t think so.