Looking in ?mapply, I executed the examples: > mapply(rep, 1:4, 4:1) [[1]] [1] 1 1 1 1
[[2]] [1] 2 2 2 [[3]] [1] 3 3 [[4]] [1] 4 > mapply(rep, times=1:4, x=4:1) [[1]] [1] 4 [[2]] [1] 3 3 [[3]] [1] 2 2 2 [[4]] [1] 1 1 1 1 I can guess that because these are 2 examples, it is no surprise that the results are different. Why is this? If ?mapply is giving me a clue, I'm not seeing it. Thanks, -Brian. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Liaw, Andy Sent: Monday, June 21, 2004 11:50 AM To: 'Ajay Shah'; r-help Subject: RE: [R] Elementary sapply question At least two ways: 1. Use extra argument in the function being sapply()'ed; e.g., > f <- function(x, y) x*x + y*y > x <- 3:5 > sapply(x, f, 3) [1] 18 25 34 [See the "..." argument in ?sapply.] 2. More generally, if both x and y are vectors (of the same length), then you can use mapply(); e.g., > x <- 1:3 > y <- 3:5 > pyth <- function(x, y) x*x + y*y > mapply(pyth, x, y) [1] 10 20 34 HTH, Andy > From: Ajay Shah > > I am discovering sapply! :-) Could you please help me with a very > elementary question? > > Here is what I know. The following two programs generate the > same answer. > > --------------------------------+----------------------------- > ----------- > Loops version | sapply version > --------------------------------+----------------------------- > ----------- > | > f <- function(x) { | f <- function(x) { > return(x*x) | return(x*x) > } | } > values = c(2,4,8) | values = c(2,4,8) > answers=numeric(3) | answers = sapply(values, f) > for (i in 1:3) { | > answers[i] = f(values[i]) | > } | > > and this is cool! > > My problem is this. Suppose I have: > pythagorean <- function(x, y) { > return(x*x + y*y) > } > > then how do I utilise sapply to replace > fixed.x = 3 > y.values = c(3,4,5) > answers=numeric(3) > for (i in 1:3) { > answers[i] = pythagorean(fixed.x, y.values[i]) > } > > ? > > I have read the sapply docs, and don't know how to tell him that the > list values that he'll iterate over "fit in" as y.values[i]. > > -- > Ajay Shah Consultant > [EMAIL PROTECTED] Department of Economic Affairs > http://www.mayin.org/ajayshah Ministry of Finance, New Delhi > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
