DZone Snippets: Mroutley's Code Snippets

Create data frame from variable number of vectors

mroutley (Matthew Routley) — Thu, 19 Apr 2007 20:08:15 GMT

// Create a data frame from a varied number of vectors
// Taken from http://article.gmane.org/gmane.comp.lang.r.general/56501/match=create+data+frame



N1 <-c(1,2,3,4)

N2 <-c(1,2,3,4)

N3 <-c(1,2,3,4)

abc <-c(1,2,3)

lab <- paste("N", seq(along=abc), sep="")

D <- data.frame(lapply(lab, get))

names(D) <- lab

Call Growl from R

mroutley (Matthew Routley) — Fri, 22 Sep 2006 02:54:18 GMT

// Send an alert to growl with the R.app icon.
// Useful for indicating the end of a long simulation.



system(paste("growlnotify -a R -t \"Message\" -m", message, sep=""))

Run R from the command line

mroutley (Matthew Routley) — Fri, 22 Sep 2006 02:52:36 GMT

// This runs R from the command line in batch mode.
// The log file is output to track R's progress



R CMD BATCH --vanilla path/to/file.R file.log &

Iteratively create objects

mroutley (Matthew Routley) — Tue, 13 Jun 2006 19:51:30 GMT

// Iteratively create objects from a list of names.
// Especially useful for creating consistent model objects for a list of data sources.
// Wrapping the assign statement in a try block is often advisable.



for(item in itemList){

	assign(paste(item, "object", sep="."),  function(get(paste(item, "data", sep=".")), options)

}

Position-based substitution in arrays

mroutley (Matthew Routley) — Fri, 21 Apr 2006 23:59:43 GMT

// Replace array values based on their row and column position
// This is an alternative to using for loops to test each position



a <- array(0, dim=c(10, 10))

a[row(a) <= col(a)*2] <- 1

Zero-inflated negative binomial

mroutley (Matthew Routley) — Mon, 10 Apr 2006 22:51:35 GMT

// Simulates a zero-inflated, negative binomial
// from Ben Bolker



rzinbinom <- function(n, mu, size, zprob) {

  ifelse(runif(n) < zprob, 0, rnbinom(n, mu=mu, size=size))

}

Spotlight queries of R documentation

mroutley (Matthew Routley) — Mon, 10 Apr 2006 21:45:59 GMT

// from http://comments.gmane.org/gmane.comp.lang.r.mac/642
// Use Spotlight to query R documentation



spotlight<-function(word) {

place<-paste(Sys.getenv("R_HOME"),"/library/",sep="")

string<-paste("mdfind -onlyin",place,word,"|",getOption("pager"))

system(string, intern=TRUE)

}