similar to: matrix of higher order differences

Two questions about matrix indexing: Is is correct that V <- V[lower.tri(V, diag=TRUE)] returns the lower triangular of matrix V, that is: all elements above diagonal are set to zero? I understand that the triangle of matrix elements of V for which lower.tri is TRUE are returned while the others (above diagonal) are set to zero (or NA ???). If D and B are vectors of logicals, what

Here's an easy question: I'd like to convert a symmetric matrix to a vector composed of the upper.tri() part of it plus the diagonal, and convert it back again. What's the best way to achieve this? I'm wondering if there are some built in functions to do this easily. I can encode fine: v <- c(diag(A),A[upper.tri(A)]) but I don't see an easy way to recover A from v

Dear All, I have a correlation matrix of size 100 x 100 and would like to extract the diagonal matrix from it. I have used the for loop to store tha correlation values of the diagonal matrix. Is there a 'R way' of doing this? Thanks in advance. Kind regards, Ezhil

Dear List: I am working to construct a matrix of a particular form. For the most part, developing the matrix is simple and is built as follows: vl.mat<-matrix(c(0,0,0,0,0,64,0,0,0,0,64,0,0,0,0,64),nc=4) Now to expand this matrix to be block-diagonal, I do the following: sample.size <- 100 # number of individual students I<- diag(sample.size) bd.mat<-kronecker(I,vl.mat) This

Hi all, Here's an interesting (for me, at least!) problem I came across: I have a correlation matrix, let's say with 6 variables, A to F, as column headings and the same 6 as row headings. The matrix is filled with correlation coefficients. Therefore, the diagonal is all 1's, and each of the two triangles formed by the diagonal has the same 15 correlation coefficients. I need to

So many matrices are square symmetrical (i.e. variance-covariance matrices), is there any way to get R to split the matrix on its diagonal and just return one diagonal? So if I have mat<-matrix(c(1,4,3,4,1,2,3,2,1), nrow = 3, ncol=3, byrow=TRUE) is there anyway to get the lower right diagonal instead of the entire symmetric matrix? -------------------------------------------

Hello R users, I would like to reduce the number of for loops in my code. I build these matrices (50000 times). The main diagonal are 1s and the two sides along the main diagonal mirror each other as follows: i<-5 fi<-matrix(0,nrow=i,ncol=i)#floral inhibition matrix for(r in 1:i){ for(c in 1:i){ if(r==c){ fi[r,c]<-1 }else if(r<c){ fi[r,c]<-1-runif(1)^.5 }else{ fi[r,c]<-fi[c,r]

Tengo una matriz de de datos (correlación) entre pares de muestras, de tipo diagonal inferior, de 250 y quisiera hacer un heatmap y/o un dendrograma. Soy un poco novato y me encuentro con el problema que no se como "importarla" para cargarla e indicar que se trata de una matriz de datos de tipo "diagonal inferior" para que R lo interprete y poder realizar un heatmap y/o

Hello! I'm trying to build a lower triangular matrix (with zeros in the diagonal) from a particular dataframe. The matrix I have to construct has 203 rows and 203 columns and that makes 20503 values to be included within (that's why I can't do it manually). To illustrate the dataframe I have, I'll give you an example of a dataframe and matrix with dimensions 6x6 (to make it

Dear all, I'm new to matrix operations in R. I couln't find a solution to the following problem among earlier help mails or in An introd to R, I guess because the question is really basic. I want to extract all above the diagonal, i.e. from 1 2 3 4 1 0 26 49 49 2 26 0 44 40 3 49 44 0 21 4 49 40 21 0 I want 26 49 44 49 40 21 Thanks in advance! Sincerely, Tord

Your message doesn't help us very much. You haven't said what kind of calculation it is you want to do, and that certainly matters. For example, for some kinds of computations the solution you started below would work fine: > M <- matrix(1:16, 4, 4) > is.na(diag(M)) <- TRUE > M [,1] [,2] [,3] [,4] [1,] NA 5 9 13 [2,] 2 NA 10 14 [3,] 3 7 NA

Hi, I am trying to work with the output of the MINE analysis routine found at http://www.exploredata.net Specifically, I am trying to read the results into a matrix (ideally an n x n x 6 matrix, but I'll settle right now for getting one column into a matrix.) The problem I have is not knowing how to take what amounts to being one half of a symmetric matrix - excluding the diagonal -

List members, Via searches I've seen similar discussion of this topic but have not seen resolution of the particular issue I am experiencing. If my search on this topic failed, I apologize for the redundancy. I am attempting to generate random covariance matrices but would like the corresponding correlations to be uniformly distributed between -1 and 1. The approach I have been using is:

Hi. I'm writing a print method for an object that includes a numeric matrix for which the lower diagonal elements are not meaningful. So I make the lower diagonal of my matrix NA and print it. But my co-author does not like NA there and wants a dash. I have tried coercing the matrix to character, essentially by M[is.na(M)] <- "-" but this interferes with the pleasing column

Hi R users I like to extract lower diagonal elements of a matrix in such a way like, data[1,2], data[1,3], ...., data[5,6] are extracted from a matrix called 'data' This short script below is what I have written so far. ########################################## data <- matrix(rnorm(36,0,1),nrow=6) temp<-c() for (i in 1:(nrow(data)-1)) { for (j in (i+1):nrow(data)) {

from ?eigen symmetric: if 'TRUE', the matrix is assumed to be symmetric (or Hermitian if complex) and only its lower triangle is used. If 'symmetric' is not specified, the matrix is inspected for symmetry. I think that could mislead a naive reader as it suggests that, with symmetric=TRUE, the result of eigen() (vectors and values) depends only on

Hi, suppose that we have a triangular upper matrix A test <- matrix(ncol = 4, nrow = 4) test[1, ] <- c(NA,1,1,1) test[2, ] <- c(NA,NA,1,1) test[3, ] <- c(NA,NA,NA,1) test[4, ] <- c(NA,NA,NA,NA) I know how quickly set diagonal value diag(test) <- 1. But how quickly set down value i.e. matrix is symmetrical? Is there in r project any quickly function? Thanks, Best Marcin

I have output from a program which produces a distance matrix I want to read into a clustering program in R. The output is a .txt file and is 'almost' lower triangular in the sense that it is just the triangle below the diagonal. So for example a 4-by-4 distance matrix appears as, 1 2 3 4 5 6 i.e. it looks like a lower triangular of a 3-by3. I thought I might be able

I need to find solutions to a tridiagonal system. By this I mean a set of linear equations Ax = d where A is a square matrix containing elements A[i,i-1], A[i,i] and A[i,i+1] for i in 1:nrow, and zero elsewhere. R is probably not the ideal way to do this, but this is part of a larger problem that requires R. In my application it is much easier (and much faster) to generate the diagonal and

Hi R user I need to read in some values from a computer program output. I can't change the output format because the developer of the program doesn't allow to change the format of output. There are two formats. First one looks like this if I have 10 variables, ------------------------------------------------------------------------------------------------------ [ 1]