similar to: Spare matrix multiplication

Displaying 20 results from an estimated 10000 matches similar to: "Spare matrix multiplication"

2013 Jan 14
2
The three-dot question
Dear all, Why does not the three-dot accept arguments from the parent environment? I am just confused with this error, can someone give me a hint? > rm(list=ls()) > testFun <- function(a, ...) + { + if(a){ + print(a) + }else + { + print(b) + } + } > > myTask <- function(a) + { + b <- 3 + testFun(a, b = b) + } >
2011 Jan 12
2
How to disable using "enter" key to exit the browser in debugging mode
Dear R, How can I disable using "enter" key to exit the browser() in debug mode? I would love to have this option because it is so annoying to jump out of the debugging mode unexpectedly when I don't want to. I guess some of us have encouraged at least one of these situations, 1, Accidentally pressed the enter key within the browser. 2, Copy and paste a piece of debugging code
2011 Jan 18
2
Convert a matrix's columns to list
Dear R, Is there an efficient way to make a list that each element is from the corresponding column of a matrix. For example, if I have a matrix "a" > a <- matrix(1:10, 5, 2) > a [,1] [,2] [1,] 1 6 [2,] 2 7 [3,] 3 8 [4,] 4 9 [5,] 5 10 I would like to have a list "b" like this > b <- list(a[, 1], a[, 2]) > b [[1]] [1] 1 2 3
2010 Oct 12
1
lapply to subsets
Dear R, I have a silly question concerns with *apply. Say I have a list called A, A <- list(a = array(1:20, c(2, 2, 5)), b = array(1:30, c(2, 3, 5))) I wish to calculate the mean of A$a, and A$b w.r.t. their third dimension so I did lapply(A,apply,c(1,2),mean) Now if I still wish to do the above task but take away some burn-in, e.g. do not take A$a[,,1:2],and A$b[,,1:2] into account.
2010 Sep 24
3
boundary check
Dear R, I have a covariates matrix with 10 observations, e.g. > X <- matrix(rnorm(50), 10, 5) > X [,1] [,2] [,3] [,4] [,5] [1,] 0.24857135 0.30880745 -1.44118657 1.10229027 1.0526010 [2,] 1.24316806 0.36275370 -0.40096866 -0.24387888 -1.5324384 [3,] -0.33504014 0.42996246 0.03902479 -0.84778875 -2.4754644 [4,] 0.06710229 1.01950917
2009 Nov 05
2
rm(list<-ls()) error
Dear R, Why rm(list<-ls()) gives an error but rm(list=ls()) not?. I remember the operator ‘<-’ can be used anywhere... Thanks! Feng -- Feng Li Department of Statistics Stockholm University 106 91 Stockholm, Sweden http://feng.li/ [[alternative HTML version deleted]]
2010 Jan 05
1
R-package related to the topic of INARMA models
Dear R, I am looking for R-package related to INARMA (Integer-valued ARMA). Can anyone give me some information? I did not get information from task view. Many thanks. Feng -- Feng Li Department of Statistics Stockholm University 106 91 Stockholm, Sweden http://feng.li/ [[alternative HTML version deleted]]
2011 Mar 23
1
R gui problem for windows
Dear R, I rare use the standard R-gui on Windows. Yesterday I tried the latest stable release on Windows 7 and XP and found one thing interesting. Assume currently I am running R code, say > example(plot) Then I click the "close window" button on the R main window. R asks me to save workspace image or not. Then I click "cancel". I suspect that my program
2011 Feb 01
1
kmeans: number of cluster centres must lie between 1 and nrow(x)
Dear R, Can't I cluster a dataset into k clusters where k is exactly the number of observations? I have version 12.2 installed. See this example > a <- matrix(1:100, 20) > kmeans(a, 20) Error: number of cluster centres must lie between 1 and nrow(x) This is a bit ad-hoc but I known R from version 2.12 allows number of clusters to be one. So I guess allowing number of clusters to be
2009 Feb 11
5
How to handle large numbers?
Dear R, I have two questions: 1, Why both R and Matlab give 0*Inf==NaN? To my knowledge, it should be zero mathematically. Am I right? 2, I need to calculate e.g. exp(a)/(exp(b)+c), where both a and b are very large numbers (>>1000, e.g a=1000, b=1007, and c=5). R gives me NaN when I use the following command: > exp(1000)/(exp(1007)+5) [1] NaN I am pretty sure this should be close to
2009 Mar 11
1
matrix multiplication, tensor product, block-diagonal and fast computation
Dear R-users, I am searching to the "best" way to compute a series of n matrix multiplications between each matrix (mXm) in an array (mXmXn), and each column of a matrix (mXn). Please find below an example with four possible solutions. The first is a simple for-loop which one might avoid; the second solution employs the tensor product but then manually selects the right outcomes. The
2011 Mar 16
2
Singularity problem
Dear R, If I have remembered correctly, a square matrix is singular if and only if its determinant is zero. I am a bit confused by the following code error. Can someone give me a hint? > a <- matrix(c(1e20,1e2,1e3,1e3),2) > det(a) [1] 1e+23 > solve(a) Error in solve.default(a) : system is computationally singular: reciprocal condition number = 1e-17 Thanks in advance! Feng --
2010 Sep 13
2
How to generate a particular sequence ?
Dear R, I have a vector, say a = c(1,2,4,5,6,8). Can I generate a vector or array (2-by-3-by-3) of this form c(1,2,1,2,1,2,4,5,4,5,4,5,6,8,6,8,6,8), in which every two elements in "a" have been repeated twice? I am to stupid today and could not figure this simple question out... Many many thanks! Feng -- Feng Li Department of Statistics Stockholm University 106 91 Stockholm,
2010 Sep 07
4
a^c(1:3)
Dear R, I have two small questions confused me recently. Now assume I have a matrix "a", like this, > a <- matrix(1:6, 2, 3) > a [,1] [,2] [,3] [1,] 1 3 5 [2,] 2 4 6 I sometimes need each row of "a" raised to a different exponent. So I do a trick like this, > a^c(2, 3) [,1] [,2] [,3] [1,] 1 9 25 [2,] 8 64 216 My first
2011 Feb 26
1
Wired behavior of a 2-by-2 matrix indicies
Dear R, I found a very wired behavior for a 2-by-2 matrix, see this example > A <- matrix(1:4, 2) > idx4A <- matrix(1:4, 2) > A[idx4A] Error in A[idx4A] : subscript out of bounds But other matrices are fine, > B <- matrix(1:9, 3) > idx4B <- matrix(1:9, 3) > B[idx4B] [1] 1 2 3 4 5 6 7 8 9 I can reproduce this for both 32bit windows and 64bit linux with R 2.12.1
2009 Feb 04
3
Passing data among multiple instances
Dear R, I have two R instances running at the same time, say instance A and instance B. Is there a simpler way to pass the data in A to B? More precise, I have a stupid example: In instance A, I am running a function "test1" test1 <- function (x1) { x2 <- sin(x1) return(x2) } In instance B, another function "test2" test2 <- function (x2) { x3 <-
2007 Oct 10
3
as.dist with diagonal unequal zero
Hello and sorry that I still haven?t found a solution for my problem. I need to extract the lower and upper triangle from a square matrix including the diagonal. This diagonal is not zero in that special case. I tried with as.dist w<-as.dist(w, diag = TRUE) > w 1 2 3 4 5 1 0 2 2 0 3 3 8 0 4 4 9 14 0 5 5 10 15 20 0 but found no way to keep the diagonal that is in the
2012 Apr 13
4
#!/usr/bin/env Rscript --vanilla ??
I think that's my first true question (rather than answer) to R-help. As R has, for a long time, become my primary scripting and programming language, I'm prefering at times to write Rscript files instead of shell scripts, notably when R has nice ways to do some of the things. On a standard standalone platform with standard R, I would start such a script with
2010 Oct 05
2
Intel i7 utilization
Hello, Is there a way to force through R the amount of the cpu's cores (or the cpu's utilization level) used under Windows 7 or Linux? Thanks, Costas
2009 Aug 06
1
solving system of equations involving non-linearities
Hi, I would appreciate if someone could help me on track with this problem. I want to compute some parameters from a system of equations given a number of sample observations. The system looks like this: sum_i( A+b_i>0 & A+b_i>C+d_i) = x sum_i( C+d_i>0 & C+d_i>A+b_i) = y sum_i( exp(E+f_i) * ( A+b_i>0 & A+b_i>C+d_i) = z A, C, E are free variables while the other