Hi, Your use of "do.call" is essentially equal to "dpois(lt$y0, exp(rowSums(t(X[lt$i,])*B[,1])))". You do not need to use "do.call", "sapply" or "apply" will do, e.g.,
> sapply(1:nrow(lt), function(x) fc(lt[x,2],lt[x,1])) [1] 0.1891356 0.1859965 0.3149658 0.3128512 0.2622549 0.2631122 Wayne (Yanwei) Zhang Statistical Research >CNA -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Kathie Sent: Monday, August 08, 2011 10:16 AM To: r-help@r-project.org Subject: [R] on "do.call" function Dear all, Even though one of R users answered my question, I cannot understand, so I re-ask this question. I am trying to use "do.call", but I don't think I totally understand this function. Here is an simple example. -------------------------------------------- > B <- matrix(c(.5,.1,.2,.3),2,2) > B [,1] [,2] [1,] 0.5 0.2 [2,] 0.1 0.3 > x <- c(.1,.2) > X <- cbind(1,x) > X x [1,] 1 0.1 [2,] 1 0.2 > > lt <- expand.grid(i=seq(1,2), y0=seq(0,2)) > lt i y0 1 1 0 2 2 0 3 1 1 4 2 1 5 1 2 6 2 2 > > fc <- function(y0,i) dpois(y0, exp(rowSums(t(X[i,])*B[,1]))) > > do.call(fc,lt) [1] 1.892179e-09 3.348160e-01 3.800543e-08 3.663470e-01 3.816797e-07 2.004237e-01 -------------------------------------------- Unfortunately, what I want to get is dpois(0, exp(rowSums(t(X[1,])*B[,1]))) = 0.1891356 dpois(0, exp(rowSums(t(X[2,])*B[,1]))) = 0.1859965 dpois(1, exp(rowSums(t(X[1,])*B[,1]))) = 0.3149658 dpois(1, exp(rowSums(t(X[2,])*B[,1]))) = 0.3128512 dpois(2, exp(rowSums(t(X[1,])*B[,1]))) = 0.2622549 dpois(2, exp(rowSums(t(X[2,])*B[,1]))) = 0.2631122 -------------------------------------------- Would you plz tell me why these two results are different?? and how do I get what I want to using "do.call" function?? Regards, Kathryn Lord -- View this message in context: http://r.789695.n4.nabble.com/on-do-call-function-tp3727262p3727262.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. NOTICE: This e-mail message, including any attachments and appended messages, is for the sole use of the intended recipients and may contain confidential and legally privileged information. If you are not the intended recipient, any review, dissemination, distribution, copying, storage or other use of all or any portion of this message is strictly prohibited. If you received this message in error, please immediately notify the sender by reply e-mail and delete this message in its entirety. ______________________________________________ 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.