Helen Yang <[EMAIL PROTECTED]> wrote: > I wonder whether there is any resource that can point to useful substitutes > for S functions that are not recognized by R. At the same time whether there > is a list of functions, which appear in both R and S but which don't do > exactly the same thing.
As Prof. Brian D. Ripley <[EMAIL PROTECTED]> said, see the FAQ at: <http://www.r-project.org/> (Click "FAQs", "R FAQ", "R and S".) Here are my own crib notes on some differences that I care about. Note "S" here really means S-Plus version 6.1.2. I have not checked whether any of these have changed since October. This list is certainly not complete. *** R vs. S (DB 10/28/02) *** Language differences: - Scoping rules differ. In R, functions see the functions they're in. Try: f1 <- function() {x <- 1; f2 <- function() print(x); f2()}; f1() - Data must be loaded explicitly in R, can be attach()'ed in S. Addressed by my contributed package "g.data". - R has a character-type NA, so LETTERS[c(NA,2)] = c(NA,"B") not c("","B") - paste("a","b", sep="|", sep=".") is an error in R; ok in S. - for() loops more efficient in R. Graphics differences: - Log scale indicated in S with par(xaxt)=="l", in R with par("xlog")==T. - R has cex.main, col.lab, font.axis, etc. Thus title("Hi", cex=4) fails. - R has plotmath and Hershey vector fonts. - R has palette(rainbow(10)) to define colors (both screen and printer). Functions missing from R: - unpaste, slice.index, colVars Functions missing from S: - strsplit, sub, gsub, chartr, formatC Functions that work differently: - system() has no "input" argument in R. - substring(s,"x") <- "X" only works in S, but R has s <- gsub("x","X",s). - scan expects numbers by default in R. - which(<numeric>) converts to logical in S, is an error in R. - The NULL returned by if(F){...} is invisible in R, visible in S. - The NULL returned by return() is visible in R, invisible in S. - Args to "var" differ, and R has "cov". S na.method="a" ~ R use="p". - var (or cov) drops dimensions in S, not R. - cut allows labels=F in R, not in S (also left.include=T becomes right=F). - Last argument of a replacement function must be named "value" in R. - tapply(1:3, c("a","b","a"), sum) is a 1D-array in R, a vector in S. -- -- David Brahm ([EMAIL PROTECTED]) ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help