similar to: vectorize an expression

Hi I am writing a bunch of functions that take two, three or four arguments. These functions operate on vectors of the same length; but I want the function to behave sensibly if one or more arguments are scalars. "+" does this for two arguments: "+"(1:10,3) # interpreted as "+"(1:10,rep(3,10)) But my functions can take more arguments. Say f() takes three:

Hi I want to extract rows of a matrix, and preserve rownames even if only one row is selected. Toy example: R> a <- matrix(1:9,3,3) R> rownames(a) <- letters[1:3] R> colnames(a) <- LETTERS[1:3] R> a A B C a 1 4 7 b 2 5 8 c 3 6 9 Extract the first two rows: R> wanted <- 1:2 R> a[wanted,] A B C a 1 4 7 b 2 5 8 rownames come through fine. Now extract just

Hi again everyone I have an arbitrarily dimensional array "a" and a list "jj" of length length(dim(a)). The elements of jj are vectors of indexes. How do I use do.call() to extract a[ jj[[1]], jj[[2]], jj[[3]], ...] ? Toy example follows: a <- matrix(1:30,5,6) jj <- list(5:1,6:1) I want the following a[ jj[[1]],jj[[2]] ] How do I do this? OBAttempts:

Hi How do I concatenate two lists element-by-element? Example: list.1 <- list(temperature=c("hot","cold") , size=c("big","medium")) list.2 <- list(temperature=c("lukewarm") , size=c("massive","tiny")) list.wanted <- list(temperature=c("hot","cold","lukewarm") ,

Hello everybody I'm using contour() to draw streamlines of potential flow, eg jj <- seq(from= -4, to=4,len=20) jj <- outer(jj,jj,function(x,y){x})+1i*outer(jj,jj,function(x,y){y}) f <- function(x){x^2} contour(Im(f(jj)), nlevels=44 , labels="") How best to put arrows on the contour lines to show the direction of flow? (ie I want contour lines looking like

Hi how do I make my axes cross at the origin? x <- seq(from=-pi,to=pi,len=30) plot(x,sin(x)) makes the axes cross at about (-pi,-1). How do I get my x and y axes to cross in the centre of the graph, with the sine curve passing through the intersection? I couldn't find anything in ?par or ?axis; searching R-FAQ for "axis" didn't help. -- Robin Hankin Uncertainty

Professor Ripley thanks for this. Very much appreciated. The original subject line reflected my late-night conviction that the answer might involve passing a strange list to do.call(). Anyway, package magic is broken (only in R-devel, I might add) because I have a function called "%eq%". R-2.0.0 CMD check is stopping (I think) because it interprets the "%" as a

Hi everyone. I'm playing with aperm(): a <- 1:24 dim(a) <- c(2,3,2,2) permutation <- c(1,2,4,3) b <- aperm(a,permutation) So if my understanding is right, a[1,3,2,1] == b[c(1,3,2,1)[permutation] ] but this isn't what I want because the RHS evaluates to a vector, and I am trying to identify a single element of b. How do I modify the RHS to give what I want? Following

Hello List I have just written a little function that takes two matrices as arguments and returns a large matrix that is composed of the two input matrices in upper-left position and lower-right position with a padding value everywhere else. (function definition and toy example below). I need nonsquare matrices and rowname() and colname() inherited appropriately. Two questions: (1) Is there a

Hi try this: p3dpairs <- function(x,x1, xlim=NULL,ylim=NULL,zlim=NULL,col=par("col"), pch=par("pch"), cex=par("cex"), ...){ if(is.matrix(x)){ z <- x[,3] y <- x[,2] x <- x[,1] } if(is.matrix(x1)){ z1 <- x1[,3] y1 <- x1[,2] x1 <- x1[,1] } if(missing(zlim)) { z.grid <-

Hi everyone suppose I have a <- array(1:256,rep(4,4)) and want to access a[1,2,3,1] by the vector c(1,2,3,1). As per yesterday, I can use do.call(): a[1,2,3,1] == do.call("[",c(list(a),c(1,2,3,1))) Now how do I apply the above technique (or indeed any other technique!) to get a[1,2,3,] [1] 37 101 165 229 from a vector like c(1,2,3,0) or c(1,2,3,NULL) or c(1,2,3,NA)?

Hello everybody. I am trying to upgrade from R-1.9.0 to R-1.9.1 on a RedHat linux 2.4.18 system. I get the following error after "tar -xvzf R-1.9.1.tgz ; cd ./R-1.9.1/ ; ./configure" and "make" : [make works for 10 minutes ... snip ...] varExp text html latex varFixed text html latex varFunc

Hi the manpage says that crossprod(x,y) is formally equivalent to, but faster than, the call 't(x) %*% y'. I have a vector 'a' and a matrix 'A', and need to evaluate 't(a) %*% A %*% a' many many times, and performance is becoming crucial. With f1 <- function(a,X){ ignore <- t(a) %*% X %*% a } f2 <- function(a,X){ ignore <-

Hello everybody I'm putting finishing touches to a library, and have noticed that the .dvi file that R CMD check creates does not sort the functions in alphabetical order. I find this odd because I used the "tidy" routines in section 3.1 of the R-exts manual, which produce R code in which the functions are alphabetically ordered (and I performed R CMD check using the

Hi guys. Check this out: > NaN +NA [1] NaN > NA + NaN [1] NA I thought "+" was commutative by definition. What's going on? > R.version _ platform powerpc-apple-darwin6.8 arch powerpc os darwin6.8 system powerpc, darwin6.8 status major 1 minor 9.0 year 2004 month 04 day 12 language R > (Both give NA under linux, so it looks

Hi [I'm not sure if this is "intelligible to non-programmers" or not] R-exts (section 4.2) gives an example of the .C() function whose third argument is "as.integer(length(a))", and urges the user to coerce all the arguments to the correct form (on pain of "hard-to-catch errors" which I now know to be very appropriate, if understated, phrasing). The

OK guys another problem. I have a 3D array "x" with dim(x)=c(a,a,b^2) and I want to rearrange the elements of x to make a matrix "y" with dimensions c(a*b,a*b). Neither a nor b is known in advance. I want the "n-th" a*a submatrix of y to be x[,,n] (where 1 <= n <= b^2). Needless to say, this has gotta be vectorized! Toy example with a=2, b=3 follows:

Hi everyone I want a square scatterplot with abline(0,1) going exactly through the SW and NE corners. By "square" I mean that the plotting region is exactly square, and that the axis limits are identical. x <- 1:20 y <- x+rep(c(-1,1),10) lims <- range(c(x,y)) None of the following do this: plot(x,y) ; abline(0,1) #not square plot(x,y,asp=1);abline(0,1) #diagonal

Hi I'm having difficulty making a package pass R CMD check. I need to read in a dataset from another package, modify it, and have the modified object available in the first package. help(require) says: The source code for a package that requires one or more other packages should have a call to 'require', preferably near the beginning of the source, and of course

Hello list. I very often need 3d scatterplots, and use scatterplot3D quite a lot. I am trying to modify persp() to plot scatterplots, and make use of the theta and phi arguments that persp() offers. I am having some difficulty passing the correct arguments to persp(). Here is my function so far. Much of it is copied from the persp() manpage. points3d <- function(x,y,z,