Harvey.Monder@pharma.com
2001-Oct-03 18:28 UTC
[Rd] RE: [R] Several R vs S-Plus issues (PR#1112)
Also in assign() there some arguments lacking in R such as 'frame' and 'where', though I guess that 'frame' in S may be similar to 'pos' in R. Harvey -----Original Message----- From: David Brahm [SMTP:a215020@agate.fmr.com] Sent: Wednesday, October 03, 2001 11:36 AM To: r-help@stat.math.ethz.ch Cc: Kurt.Hornik@ci.tuwien.ac.at; r-bugs@r-project.org Subject: [R] Several R vs S-Plus issues Hi, all, I've been converting code from S-Plus ("S" for short) to R for a few weeks. Here are some differences I've found, aside from the big well-known ones (scoping, models, data storage) and the contents of Kurt Hornik's FAQ section 3.3.3. Let me start with the ones that seem like serious bugs or deficiencies: 1) LETTERS[c(NA,2)] in S is c("","B"), but in R is c("NA","B"). This is TERRIBLE! I have a ton of S-Plus code that looks like: y$ticker <- z$ticker[match(y$cusip, z$cusip)] and I count on a ticker of "" to indicate failed lookups. Not only will I need to change all that code, but I'll never be able to trade Nabisco (ticker NA) again. PLEASE re-consider this choice, or at least make it an option: option(na.char=""). 2) system() has no "input" argument in R. Here's a (Unix) example: S> system("cd mydir; latex myfile", input="x") which goes to the directory where myfile lives and LaTeX's it, passing an "x" through STDIN in case LaTeX encounters an error. My R fix is: R> system("cd mydir; echo x | latex myfile") Note that it's not as simple as cmd <- paste("echo",input,"|",cmd). 3) R> myfun <- function(x, ...) {x[...] <- 0; x} R> myfun(3) Error in myfun(3) : SubAssignArgs: invalid number of arguments It failed because no ... was given. Fortunately, this is easily patched: R> myfun <- function(x, ...) {if (missing(...)) x[]<-0 else x[...]<-0; x} 4) Missing functions: a) identical() [scheduled for 1.4.0] b) slice.index() c) rowSums(), colSums(), colVars(), etc. d) unpaste() - R has strsplit, whose result is like the transpose of unpaste 5) rowsum() gives character dimnames in S, factor numbers in R. I've reported this early, and Brian D. Ripley promised a fix in 1.4.0. OK, the rest are just differences, not complaints. In fact, sometimes they are very good differences. 1) Same argument given twice produces an error in R; S takes the last one. S> mean(x=4, x=5) # Returns 5 R> mean(x=4, x=5) # Error 2) row.names(y) <- LETTERS[1:3] coerces list to dataframe in S, is error in R. 3) Default "what" for scan in S is "", in R is double(0). 4) Default "quote" for scan is "'\"" in R, causes different behavior than S. 5) which(<numeric>) converts to logical in S, is an error in R. 6) The NULL returned by if(F){...} is invisible in R, visible in S. 7) The NULL returned by return() is visible in R, invisible in S. 8) Args to "var" differ, and R has "cov". S na.method="a" is like R use="p". 9) var (or cov) drops dimensions in S, not R. 10) cut allows labels=F in R, not in S (also left.include=T becomes right=F). 11) substring(s,"x") <- "X" only works in S, but R has s <- gsub("x","X",s). 12) S function casefold() replaced in R by toupper() or tolower(). 13) Functions missing from S: sub(), gsub(), chartr(), toupper(), tolower() 14) Log scale indicated in S with par(xaxt)=="l", in R with par("xlog")==T. -- David Brahm (a215020@agate.fmr.com) -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-. -.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. _._ -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._