similar to: how to efficiently extract elements of a list?

I can define a list containing NULL elements: > myList <- list("aaa",NULL,TRUE) > names(myList) <- c("first","second","third") > myList $first [1] "aaa" $second NULL $third [1] TRUE > length(myList) [1] 3 However, if I assign NULL to any of the list element then such element is deleted from the list: > myList$second <-

For a long time I've wanted a way to conveniently extract multiple elements from a list, which [[ doesn't allow. Can anyone suggest an efficient function to do this? Wouldn't it be a sensible addition to R? For example, alist <- list() alist[[1]] <- list() alist[[1]]$name <- "first" alist[[1]]$vec <- 1:4 alist[[2]] <- list() alist[[2]]$name <-

Dear R-Helpers: I am a entry level user of R. Have the following question. Many thanks in advance. # value.vec stores values value.vec <- c('a','b','c') # which.vec stores the locations/indexs of values in value.vec. which.vec <- c(3, 2, 2, 1) # How can I obtain the following vector based on the value.vec and which.vec mentioned above # vector.I.want <-

Dear list members, Where can I find code for computing the p*p variance-covariance matrix given a vector of p variances (ordered varA, varB, ..., varp) and a vector of all possible correlations (ordered corAB, corAC, ..., corp-1,p)? I know that the covariance between 2 variables is equal to the product of their correlation and their standard deviations: corAB * varA^.5 * varB^.5 and so:

Hello I have a time-comsuming program which need to simplify, I have tested the annotated program as follow: > #define function which will be call > calsta <- function(c, n=100000) + { + i <- seq(from=0, length=c) + logx <- lchoose(NT-n, CT-i) + lchoose(n, i) + logmax <- max(logx) + logmax + log(sum(exp(logx - logmax))) + } > CT=6000 #assignment to CT >

I have a very long list of strings. Each string actually contains multiple values separated by a semi-colon. I need to turn each string into a vector of the values delimited by the semi-colons. I know I can do this very laboriously by using loops, nchar, and substr, but it is terribly slow. Is there a basic R function that handles this situation? If not, is there perhaps a faster way to do it than

Hello everyone, Considering the following code sample : ---- indexes <- function(vec) { vec <- which(vec==TRUE) return(vec) } mat <- matrix(FALSE, nrow=10, ncol=10) mat[1,3] <- mat[3,1] <- TRUE ---- Issuing apply(mat, 1, indexes) returns a 10-cell list, as expected. Now if I do: ---- mat[1,3] <- mat[3,1] <- FALSE apply(mat, 1, indexes) ---- I would expect a

I have a simple vector, called tmp that I want to subset based on another vector called vec. Everything works as expected except for below where the subsetting returns something other than the original data. Any ideas? > vec <- c(1,2,3,4,5,59,60,27,32,21) > tmp [1] 1.0 1.1 2.0 2.1 2.2 3.0 3.1 4.0 5.0 5.1 6.0 7.0 8.0 8.1 9.0 [16] 9.1 9.2 10.0 10.1 11.0 12.0 13.0 14.0

Dear R-gurus, I would like to use a lapply on a kind of "bivariate" problem. I have a vector and a list, components of which are vectors, e.g. vec <- c(1,2,3) lst <- list(1, c(2,3), c(4,5,6)) I want to apply a function to each component of the list, using the corresponding component of the vector as a parameter. E.g. I want a list in the form list(lst[[1]] + vec[1], lst[[2]]

Hello R-help - I have vec <- c("string1", "string2", "string3") ind <- list(c(1,2),c(1,2,3)) I want "vec" indexed by each vector in the list "ind". The first element of the list I want would be vec[c(1,2)], the second element would be vec[c(1,2,3)], like the following. [[1]] [1] "string1" "string2" [[2]] [1]

I don't understand how this function can subset by i when i is missing.... ## My function: myfun = function(vec, i){ ret = vec[i] ret } ## My data: i = 10 vec = 1:100 ## Expected input and behavior: myfun(vec, i) ## Missing an argument, but error is not caught! ## How is subsetting even possible here??? myfun(vec) Is there a way to check for missing function arguments, *and*

I am trying to convert a string to a vector, and I'm stuck! Suppose you have a string of numbers (string) that you want to convert to a vector (vec). I am able to split the string turning it into a list by using strsplit, but this makes a list, which I can't seem to access the way that I'd like to (it becomes a character list of only one(?!?) element.)

I want to try to get a result of element wise addition between a vector and a list. It can be done with "for statement." In order to reducing computing time, I have tried to avoid "for state." If anybody give me an idea, I would apprecite it much. for example, with a & b as below lines, a<- list(c(1,3),c(1,2),c(2,3)) b<-c(10,20,30) I would like to have a list (like

Hi All: I'm looking to find out a bit more about how subassignment actually works and am hoping someone with knowledge of the details can fill me in (I've looked at the source code, but my knowledge of C is lacking). In the case of vectors, my reading of ?"[" would indicate that for a vector, vec <- 1:25, vec[c(1,5,25)] <- c(101,102,103)is functionally the same as

Hi! I'm new to R and have problems with the following code: <code> awprob<-c(0.4,0.4,0.1,0.1) awsample<-sample(c(1:4),3,awprob,replace=TRUE) vec<-vector(mode="numeric",10000) vec[]<-sum(sample(c(1:4),20,awprob,replace=TRUE)) </code> My problem: The elements of vec have the same value. How can I tell R that I want to have a *new* sample for each value and

Dear R friends: Can someone help me with the following problem? Many thanks in advance. # Problem Description: # I want to write functions which take a (character) vector of dataframe names as input argument. # For example, I want to extract the number of observations from a number of dataframes. # I tried the following: nobs.fun <- function (dframe.vec) { nobs.vec <-

Hi all, I would like to combine elements of a vector: vec <- c("astring", "b", "cstring", "d", "e") > vec [1] "astring" "b" "cstring" "d" "e" such that for every element that contains "string" at the end, it is combined with the next element, so that I get this:

Good evening I often have as output from simulations a list of various values, vectors and matrices. Supposing that I then run said simulation several times, I often want to extract a particular result from each simulation for plotting and, ideally, put it in a matrix. A simple example v1 <- 1:5 v2 <- 6:10 other1 <- "stuff" other2 <- "stuff" set1 <-

Hi, Your mistake seems to be in sum(v[1:x]) You create "x" as a vector but your treat it as a single number. v[1:x] expects "x" to be a single number and only considers its first element which is 1. If I understand your query correctly, the following might handle your problem: sum.vec <-NULL for (x in 1:1000){ t <- rbinom(1000, 1, 0.5) v <- replace(t,t==0,-1)

Suppose, I have following vec <- vector("list", length=3) for (i in 1:3) vec[[i]] <- matrix(rnorm((i+3)*2), (i+3)) vec Now I want to change the type of "vec" from list to a matrix with (4+5+6) rows and 2 columns. How can I do that? Thanks and regards, -- View this message in context: http://www.nabble.com/From-%22list%22-to-%22matrix%22-tp24345922p24345922.html Sent