search for: mapply

Hello! I have noticed that mapply() drops names in R 2.3.1 as well as in r-devel. Here is a simple example: l <- list(a=1, b=2) k <- list(1) mapply(FUN="+", l, k) [1] 2 3 mapply(FUN="+", l, k, SIMPLIFY=FALSE) [[1]] [1] 2 [[2]] [1] 3 Help page does not indicate that this should happen. Argument USE.NAMES...

Hello all I would like to ask your help use mapply. I have a function called findCell that takes two arguments(x,sr) where x is a vector of size two (e.g x<-c(2,3) and sr is a matrix. I would like to call many times the findCell function (thus I need mapply) for different x inputs but always for the same sr. as x is a vector of size two (two...

Hi, Starting with ordinary vectors, so we know what to expect: > mapply(function(x, y) {x * y}, 101:106, rep(1:3, 2)) [1] 101 204 309 104 210 318 > mapply(function(x, y) {x * y}, 101:106, 1:3) [1] 101 204 309 104 210 318 Now with an S4 object: setClass("A", representation(aa="integer")) a <- new("A", aa=101:106)...

...colum contains the values to assign to them: : kkk <- data.frame(vars=c("var1", "var2", "var3"), vals=c(10, 20, 30), stringsAsFactors=F) If I do : assign(kkk$vars[1], kkk$vals[1]) it works : var1 [1] 10 However, if I try with mapply this is what I get: : mapply(assign, kkk$vars, kkk$vals) var1 var2 var3 10 20 30 : var2 Error: object 'var2' not found Maybe I have not undestand how mapply and assign work. Do you have any comments? Thanks, -Sergio.

...it and asked if there was a better solution. rawdata <- data.frame(rbind(c(1,2,2), c(4,5,6))) sens <- c(2,4,6) temp <- t(rawdata)/sens temp <- t(temp) print(temp) Gabor sent three other solutions and I understood 2 of them but not the one below. I think I understand mapply a little but what I don't understand how it knows to take the rows of rawdata and then I guess recycle sens ? how did the mapply know not to take the columns of rawdata and do something to them ? or maybe mapply does things element by element and it is doing more complex recycling ? I gu...

I get an error when using self-defined (not standard) functions with mapply with S4 objects from the raster package that I develop: "Error in as.character(sys.call(sys.parent())[[1]]) : cannot coerce type 'closure' to vector of type 'character'". Does anyone understand why? The problem is illustrated below. Thanks, Robert > # First a gener...

List: Thank you for the replies to my post yesterday. Gabor and Phil also gave useful replies on how to improve the function by relying on mapply rather than the explicit for loop. In general, I try and use the family of apply functions rather than the looping constructs such as for, while etc as a matter of practice. However, it seems the mapply function in this case is slower (in terms of CPU speed) than the for loop. Here is an example....

Hi, I have a problem that I'm finding a bit tricky. I'm trying to use mapply and assign to generate curried functions. For example, if I have the function divide divide <- function(x, y) { x / y } And I want the end result to be functionally equivalent to: half <- function(x) divide(x, 2) third <- function(x) divide(x, 3) quarter <- function(x) divide(x, 4)...

I can run one-sample t-test on an array, for example a matrix myData1, with the following apply(myData1, 2, t.test) Is there a similar fashion using apply() or something else to run 2-sample t-test with datasets from two groups, myData1 and myData2, without looping? TIA, Gang

Hello everybody. I've been experimenting with mapply(). Does anyone else have problems with: R> mapply(rep,times=1:4, MoreArgs=42) (I get a seg fault). robin R> R.version _ platform powerpc-apple-darwin6.6 arch powerpc os darwin6.6 system powerpc, darwin6.6 status beta major 1 minor 8.0 year 2003 month...

Dear all, I am having a problem with mapply. I guess the reason is that mapply is not "vectorized". But could you please take a look at my code below and help me to find a solution (either a better way to use mapply or a different function to call). Thanks a lot! ##beginning of my code myfun <- function(threshold, all.data) {...

Vectorize is defined to return a function that acts as if 'mapply' was called. So we have: > mapply(dput,1:2) # mapply form 1L # calls dput on each element of 1:2 2L [1] 1 2 > Vectorize(dput)(1:2) # Vectorize form 1L # same behavior 2L [1] 1 2 Same thing wit...

...data of different sizes testdf1 <- makeTestDF(100) testdf2 <- makeTestDF(200) #Define a formula and call coxph form <- Surv(times, event) ~ trt coxph(form, testdf1) #Works coxph(form, testdf2) #Works #Create a list of the two data.frames df.list <- list(testdf1, testdf2) #Try to use mapply mapply(coxph, form, df.list) ### END R SAMPLE CODE ############################### The mapply call generates the following message: Error in terms.default(formula, special, data = data) : no terms component It appears from debugging that the formula argument passed into coxph is simply `~` in...

Thanks for both the mapply and array approaches! However, although intended to generate the same result, they don't: # mapply approach n = 3 sa <- rnorm(n,0.8,0.1) so <- rnorm(n,0.5,0.1) m <- rnorm(n,1.2,0.1) mats = mapply(function(sa1, so1, m1) matrix(c(0,sa1*m1,so1,sa1),2,2,byrow=T), sa, so, m, SIMPLIFY =...

--KsGdsel6WgEHnImy Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit Hi, people. Wandering in R archives, and seeing the message attached below, I noticed that: mapply(rep,times=1:4, MoreArgs=42) still segfaults on R 2.2.0, and thought I should be a good citizen and report it, even if I do not have an actual problem with this. :-) > version _ platform i686-pc-linux-gnu arch i686 os linux-gnu system i...

...t;- list(list(c(1, -1, -1, 1, 1),c(1, 1, -1, -1, -1)), list(c(1, 1, 1, 1, 1),c(1, 1, -1, 1, -1))) x y #I need merge x and y, I have tried with list.uni <- vector("list", length(x)) for (i in 1:length(x)) { for (j in 1:length(x[[1]])) { list.uni[[i]][[j]] <- mapply(cbind, x[[i]][[j]], y[[i]][[j]], SIMPLIFY=FALSE) } } list.uni I have learn about ?lapply, ?sapply and ?mapply but I still didn't understand how to use it. I need the result...

Hello, I would like to use mapply to avoid using a loop but for some reason, I can't seem to get it to work. I've included copies of my code below. The first set of code uses a loop (and it works fine), and the second set of code attempts to use mapply but I get a "subscript out of bounds" error. Any guidance woul...

Hi, > ... Wrong. It looks like internally a[[1]] is always used instead of a[[i]]. > The real problem it seems is that 'a' is treated as if it was of > ength 1: > > > mapply(function(x, y) {x * y}, a, 1:3) > [1] 101 202 303 > > mapply(function(x, y) {x * y}, a, 5) > [1] 505 > > In other words, internal dispatch works for [[ but not for length(). Documentation of mapply says > Arguments are recycled if necessary. So, the function seems to wo...

..., ncol=5), matrix(rnorm(50), ncol=5)) b <- list(matrix(rnorm(50), nrow=5), matrix(rnorm(50), nrow=5)) I don't recall how to perform matrix multiplication on each list element such that the result is a new list result <- list(a[[1]]%*%b[[1]], a[[2]]%*%b[[2]]) I think I'm close with mapply(), but I'm doing something silly mapply('%*%', a,b) Thanks. Harold [[alternative HTML version deleted]]

Dear list, this works fine: x <- split(iris, iris$Species) x1 <- lapply(x, function(L) transform(L, g = L[,1:4] * 3)) but I would like to multiply each Species with another factor: setosa by 2, versicolor by 3 and virginica by 4. I've tried mapply but without success. Any thoughts? Thanks for any idea! Patrick