similar to: idea for "virtual matrix/array" class

Hi. I'm new to R, and I'm still learning R's system for addressing subsets of data structures. I'm particularly interested in the problem of selecting subarrays based on complex criteria involving the dimnames (as opposed to the values of the cells) of the array. Here's an example of such a problem. Suppose I have an array x of unknown dimensions (it may have been passed as

Hi, I recently encountered a problem with array subsetting and came up with a fix. Given an array of arbitrary dimensions, in which the number of dimensions is only known at runtime, I wanted to extract a subarray. The main issue with doing this is that in order to extract a subarray from an array of (say) 4 dimensions you usually specify something like this a.subarray <- a[,c(4,2),1:5,]

Define an array > v<-1:256 > dim(v)<-rep(4,4) Subarrays can be obtained as follows: > v[3,2,,2] [1] 71 87 103 119 > v[3,,,2] [,1] [,2] [,3] [,4] [1,] 67 83 99 115 [2,] 71 87 103 119 [3,] 75 91 107 123 [4,] 79 95 111 127 In the general case this procedure is very tedious. Given an array A, dim(A)=(dim_1,dim_2,...,dim_d) and two vectors

useR's I have a matrix from which I want to take multiple subsets from, according to a particular scheme I will now describe. The matrix below (mat) is 5x5, and I want to take 9 subsets of it, each of dimension 3x3. The best way to explain what the result should look like is with the following: > dat <- c(3,6,1,9,12,9,2,10,6,5,3,13,1,4,8,9,4,6,10,11,2,7,3,5,10) > miss <-

I wonder what's the right way in R to do the following -- placing objects of the same kind together in subarrays of varying length. Here's what I mean: > word <- c("a","b","c","d","e","f","g","h","i","j") > kind <- c(1,1,1,2,3,4,5,5,7,7) > d <-

useR's, I need help getting a Fortran DLL successfully returning the correct output. The attached fortran source code (filter2d.f) and DLL (filter2d.dll) are attached. Also, I attached a text file for which I want to apply the filter to (time702.txt). Here is what I am doing... > dyn.load("C:/f/NEW/filter2d.dll") > is.loaded("filter2d") [1] TRUE Then I pass the

class Array # break an array up into <size> chunks def chunk(size=1) return self if self.empty? raise ArgumentError if !size.kind_of? Integer y = self.length.divmod(size) rows = (y[1] > 0) ? y[0] + 1 : y[0] arr = Array.new(rows) (0...rows).each do |i| arr[i] = self.slice(size*i, size) end (arr.last.length...size).each { |i| arr.last[i] = nil }

Hi, I have a matrix of say 1024x1024 and I want to look at it in chunks. That is I'd like to divide into a series of submatrices of order 2x2. | 1 2 3 4 5 6 7 8 ... | | 1 2 3 4 5 6 7 8 ... | | 1 2 3 4 5 6 7 8 ... | | 1 2 3 4 5 6 7 8 ... | ... So the first submatrix would be | 1 2 | | 1 2 | the second one would be | 3 4 | | 3 4 | and so on. That is I want the matrix to be evenly divided

I've dug around but not been able to find anything, am probably missing something obvious. How can I fill a three-dimensional (or higher dimension) array by rows instead of columns. eg new1 <- array(c(1:125), c(5,5,5)) works fine for me but fills it by columns and new2 <- array(c(1:125), c(5,5,5), byrow=TRUE) throws an error. Am I missing something obvious? I also tried

there are really two related problems here I have a 2D matrix A <- matrix(1:100,nrow=20,ncol =5) S <- matrix(1:10,nrow=2,ncol =5) #I want to subtract S from A. so that S would be subtracted from the first 2 rows of #A, then the next two rows and so on. #I have a the same problem with a 3D array # where I want to subtract Q for every layer (1-10) in Z # I thought I solved this one

Hello, A simple question, although I can't find an answer via my google/forum search: I have a 4-dimensional array; call it A[1:M,1:N,1:P,1:Q]. I have a vector x that is N by 1. I would like to "quickly" add x to the 2nd dimension of A; in other words, I want a quicker way of doing the following: for (m in 1:M) { for (p in 1:P) { for (q in 1:Q) { A[m,,p,q] =

aperm() was designed for multidimensional arrays, but is also useful for table objects, particularly with the lattice, vcd and vcdExtra packages. But aperm() was designed and implemented before other related object classes were conceived, and I propose a small tune-up to make it more generally useful. The problem is that aperm() always returns an object of class 'array', which

Dear r-help, I have an array a1 with dimensions [1:660,1:65,1:25] I would like the first dimension to be the last one. That is I want and array [1:65,1:25,1:660] The only way to do this, I know, is tmp.a<-array(dim=dim(a1)[c(2,3,1)]) for(i in 1:dim(a1)[1]) tmp.a[,,i]<-a1[i,,] a1<-tmp.a rm(tmp.a) Is it possible to avoid 'for' loop here? Thank you! ---

Hi, R is having the following weird behavior and I am not sure if that is a feature or a bug: I am working on the following "3D" array: > bIm , , 1 [,1] [1,] TRUE [2,] TRUE [3,] TRUE [4,] TRUE [5,] TRUE > class(bIm) [1] "array" > dim(bIm) [1] 5 1 1 When I try to get the first 2D subarray, the whole thing folds into a vector: > bIm[,,1] [1] TRUE TRUE TRUE

I'm attempting to sort a 3 dimensional array that looks like this > x , , 1 [,1] [,2] [1,] 9 9 [2,] 7 9 , , 2 [,1] [,2] [1,] 6 5 [2,] 4 6 , , 3 [,1] [,2] [1,] 2 1 [2,] 3 2 Such that it ends up like this .... > y , , 1 [,1] [,2] [1,] 2 1 [2,] 3 2 , , 2 [,1] [,2] [1,] 6 5 [2,] 4 6 , , 3 [,1] [,2]

I would like to reference array dimensions by name in an apply and a summary function. For example: apply(x, "workers", sum) Is there a better way to do this than creating a new attribute for the array and then creating new methods for apply and summary? I don't want to name the individual elements of each dimension (such as with dimnames) but rather name the dimensions. Thanks

Dear all, When I coerce a vector into a multi dimensional array, I would like R to start filling the array along the last dimension, then the 2nd last etc. Let's jump straight into an example. x <- 1 : 24 y <- array(dim=c(2,2,6)) I would like to have: y[1,1,1] = 1 y[1,1,2] = 2 ... y[1,1,6] = 6 y[1,2,1] = 7 y[1,2,2] = 8 ... y[2,1,1] = 13 ... y[2,2,1] = 19 if I do y<- array(x,

Hi Listers, Is there a way that I can transpose an array... Suppose I have the following array... x<-array(c(1,2,3,4),dim=c(1,2,2)) , , 1 [,1] [,2] [1,] 1 2 , , 2 [,1] [,2] [1,] 3 4 And I would like to get the following result... , , 1 [,1] [1,] 1 [,2] 2 , , 2 [,1] [,2] [1,] 3 [,2] 4 Thanks in advance, Marcio -- View this message in context:

Dear all, I define , for n=5 or any integer greater than 0. A<-array((1/2)^n , c(rep(2,n))) then for any i not equal to j, and 1<=i,j<=n, B<-apply(a,c(i,j),sum) now B is a 2 by 2 matrix, I also define another costant 2 by 2 matrix G, How can I change the values of each elements of array A, according the rule that, for example, i=3,j=5,

i'm somehow embarrassed to even ask this, but is there any built-in method for doing this: my_list <- list() my_list[[1]] <- matrix(1:20, ncol = 5) my_list[[2]] <- matrix(20:1, ncol = 5) now, knowing that these matrices are identical in dimension, i'd like to unfold the list to a 2x4x5 (or some other permutation of the dim sizes) array. i know i can initialize the array, then