Why do you want to do this via character strings at all? You have at least two alternatives. First, you can pass the exponents as a vector and the data as a matrix and then just do the calculation:
f <- function(mat, expon) { apply(mat, 1, function(x, e) sum(x^e), e=expon) #this relies on the vectorised nature of R and particularly operators like ^ } f(a, 1:3) # [1] 1368 1779 2264 2829 3480 Alternatively, pass a function to your function: f2 <- function(mat, fun, ...) { apply(mat, 1, fun, ...) } f.to.pass <- function(x, e) sum(x^e) f2(a, f.to.pass, e=1:3) # [1] 1368 1779 2264 2829 3480 ________________________________________ From: r-help-boun...@r-project.org [r-help-boun...@r-project.org] On Behalf Of greatest.possible.newbie [daniel.h...@gmx.net] Sent: 08 August 2012 22:16 To: r-help@r-project.org Subject: Re: [R] Pass Conditional & loop argument into a function Ok I see that point with the quotes. But what I want to do still doesn't work: a <- matrix(1:15,ncol=3) b <- paste( paste("a[," ,paste(1:3), "]",sep="") ,"^",1:3,sep="",collapse="+") b #[1] "a[,1]^1+a[,2]^2+a[,3]^3" #instead of (which I want) a[,1]^1+a[,2]^2+a[,3]^3 #[1] 1368 1779 2264 2829 3480 or I want to change some function input (dramatically) just by changing two conditional arguments (in my case constant and c). a <- matrix(1:15,ncol=3) b <- matrix(NA,nrow=nrow(a),ncol=ncol(a)) constant <- 1 c <- 5 for (j in 1:ncol(a)) b[,j] <- mapply(function(x){ if(is.null(constant)) {paste(paste("x^", paste(1:c) , sep="", collapse=" + ") , ", a[,",j,"]" ,sep=" ") } else if(!is.null(constant)) {paste(paste(constant, paste("x^", paste(1:c) , sep="",collapse="+"),collapse="+") , ", a[,",j,"]" ,sep=" ") } }) By the way.. Can anyone tell my why collapse doesn't work in outer paste function? -- View this message in context: http://r.789695.n4.nabble.com/Pass-Conditional-loop-argument-into-a-function-tp4639580p4639681.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ******************************************************************* This email and any attachments are confidential. Any use...{{dropped:8}} ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.