Articles by Abhijit

RStudio 0.94.92 visited

July 30, 2011 | Abhijit

I just updated my RStudio version to the latest, v.0.94.92 (will this asymptotically approach 1, or actually get to 1?). It was nice to see the number of improvements the development team has implemented, based I’m sure on community feedback. The team has, in my experience, been extraordinarily responsive to user ... [Read more...]

A word of warning about grep, which and the like

July 13, 2011 | Abhijit

I’ve often selected columns or rows of a data frame using grep or which, based on some property. That is inherently sound, but the trouble comes when you wish to remove rows or columns based on that grep or which call, e.g., which would remove columns with a .1 ... [Read more...]

SAS, R and categorical variables

July 13, 2011 | Abhijit

One of the disappointing problems in SAS (as I need PROC MIXED for some analysis) is to recode categorical variables to have a particular reference category. In R, my usual tool, this is rather easy both to set and to modify using the  relevel command available in base R (in ... [Read more...]

An enhanced Kaplan-Meier plot

March 8, 2011 | Abhijit

We often see, in publications, a Kaplan-Meier survival plot, with a table of the number of subjects at risk at different time points aligned below the figure. I needed this type of plot (or really, matrices of such plots) for an upcoming publication. Of course, my preferred toolbox was R ... [Read more...]

RStudio: a cut above

March 1, 2011 | Abhijit

As most followers of and the Twitter #rstats know by now, RStudio is a new open-source IDE for R that was beta-released yesterday. I have started putting it through its paces within my R workflow, and my impressions are more than favorable. I also tried it out on ... [Read more...]

The split-apply-combine paradigm in R

February 25, 2011 | Abhijit

Last night at the DC R Users meetup, which was our largest meetup to date, I gave an introductory presentation on data munging, and spent a bit of time on the split-apply-combine paradigm that I use almost daily in my work. I talked mainly about the packages plyr and doBy, ... [Read more...]

ggplot2 joy

February 25, 2011 | Abhijit

I’ve been working on a long-term (25+yr) longitudinal study of rheumatoid arthritis with my boss. He just walked in and asked if I could create a plot showing the trajectory of pain scores over time for each subject, separated by educational level (4 groups). Having now worked with ggplot2 for ... [Read more...]

Quick and dirty parallel processing in R

April 30, 2010 | Abhijit

R has some powerful tools for parallel processing, which I discovered while searching for ways to fully utilize my 8-core computer at work. What surprised me is how easy it is…about 6 lines of code, if that. Given that I wasn’t allowed to install heavy duty parallel-processing systems like ... [Read more...]

R amusements

March 5, 2010 | Abhijit

On a lark, and to kill a bit of time, I was running the R fortune command looking for references to SAS. Here’s what two successive random fortunes turned up. Can there be two more antipodal opinions about the same product? I laughed out loud. __ fortune(‘SAS’) There are ... [Read more...]

Workflow with Python and R

March 6, 2009 | Abhijit

I seem to be doing more and more with Python for work over and above using it as a generic scripting language. R has been my workhorse for analysis for a long time (15+ years in various incarnations of S+ and R), but it still has some deficiencies. I’m finding ... [Read more...]
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