Remove files with a specific pattern in R

A quick basic tip which can come in handy whether you need to rapidly remove files from a directory:

junk <- dir(path="your_path", pattern="your_pattern") # ?dir
file.remove(junk) # ?file.remove

Clearly, for advanced needs, you can use system() and all the unix tools installed onto your machine.

Set the significant digits for each column in a xtable for fancy Sweave output

This tip may be useful in the situations when you need to set the number of digits to print for the different columns in a matrix/data.frame to be outputted as a LaTeX table.
 For example:

#install.packages("xtable")
#library(xtable)
tmp <- matrix(rnorm(9), 3, 3)
xtmp <- xtable(tmp)
digits(xtmp) <- c(0,0,3,4)
print(xtmp, include.rownames = FALSE) # row names suppressed

See here for a nice gallery depicting a large variety of outputs you can produce using the xtable package.

Iran Election analyzed with R

Here you can find a very interesting post depicting the R strengths in 'real-time statistics'.
I'd like to use the occasion to thank David Smith for hosting the best, imho, blog on R! 
Follow Him on Twitter: @revodavid .

Replacing 0 with NA - an evergreen from the list

This thread from the R-help list describe an evergreen tip that, at least once, is proved useful in R practice.

Two plot with a common legend - base graphics

If you need to share a common legend between two graphs using the ggplot2 package/paradigm take a look at this post from the Learning R blog.
The code below solves the same task using the R base graphics.

png( "2plot1legend.png", width = 480, height = 680)
par(mfrow = c(2, 1), oma = c(0, 0, 0, 2))
plot(hp~mpg, data=mtcars, col=cyl,pch=19)
plot(disp~wt, data=mtcars, col=cyl,pch=19)
par(xpd=NA)
#legend(locator(1), legend=as.numeric(levels(factor(mtcars$cyl))), pch=19, col= as.numeric(levels(factor(mtcars$cyl))) )
legend(x=5.6, y=690, legend=as.numeric(levels(factor(mtcars$cyl))), pch=19, col= as.numeric(levels(factor(mtcars$cyl))) )
dev.off()

Nice Interview

Here you can read a nice interview with David Smith, REvolution Computing’s Director of Community, statistician and bloggeR.

R Journal 1/1

R Journal 1/1 is out! Download it from here.