Displaying 20 results from an estimated 6000 matches similar to: "Pairwise Distances -- How to vectorize the loop"
2003 Apr 02
2
lme parameterization question
Hi,
I am trying to parameterize the following mixed model (following Piepho
and Ogutu 2002), to test for a trend over time, using multiple sites:
y[ij]=mu+b[j]+a[i]+w[j]*(beta +t[i])+c[ij]
where:
y[ij]= a response variable at site i and year j
mu = fixed intercept
Beta=fixed slope
w[j]=constant representing the jth year (covariate)
b[j]=random effect of jth year, iid N(0,sigma2[b])
a[i]=random
2009 Oct 13
2
How to choose a proper smoothing spline in GAM of mgcv package?
Hi, there,
I have 5 datasets. I would like to choose a basis spline with same knots in
GAM function in order to obtain same basis function for 5 datasets.
Moreover, the basis spline is used to for an interaction of two covarites.
I used "cr" in one covariate, but it can only smooth w.r.t 1 covariate. Can
anyone give me some suggestion about how to choose a proper smoothing spline
2002 Sep 12
1
Problem with indexing
Dear List
I am having a bit of a problem getting a program to work.
For each of i=1 to n persons I have a matrix (different for each person) with
m rows.
What I want to do, is create m new data sets such that the first is made up
of the first row for each person from the original matrices, the second
contains the second row for each person from the original matrices etc etc up
to the mth
2009 Jun 25
2
crr - computationally singular
Dear R-help,
I'm very sorry to ask 2 questions in a week. I am using the package
'crr' and it does exactly what I need it to when I use the dataset a.
However, when I use dataset b I get the following error message:
Error in drop(.Call("La_dgesv", a, as.matrix(b), tol, PACKAGE = "base")) :
system is computationally singular: reciprocal condition number =
2007 Nov 15
5
Multiply each column of array by vector component
Hi,
I've got an array, say with i,jth entry = A_ij, and a vector, say with jth
entry= v_j. I would like to multiply each column of the array by the
corresponding vector component, i,e. find the array with i,jth entry
A_ij * v_j
This seems so basic but I can't figure out how to do it without a loop.
Any suggestions?
Michal.
2008 Mar 15
2
Please find the error in my code
hello everybody
I use the following code for my programming & it runs with the error as specified below.Any help that would disolve the error will be highly appreciated.
Thanks in advance
my code looks like this
#### R programme for simulating the power of the two sample t test vs various
#### non-parametric alternatives
sim.size <- 200
sample.size <- 10
set.seed(231)
mu1 <- 0
delta
2008 Nov 10
2
how to convert indvidual pairwise distances to matrix
Hello,
I am trying to convert list of pairwise distances to a distance matrix for
spatial analysis (kriging). For instance, I have something like this for
each pair pf points, and I want to convert it to a matrix:
point1 point2 distance
1 1 0
1 2 4
2 2 0
2 1 4
Please let me know if there is a
2005 Jun 15
2
need help on computing double summation
Dear helpers in this forum,
This is a clarified version of my previous
questions in this forum. I really need your generous
help on this issue.
> Suppose I have the following data set:
>
> id x y
> 023 1 2
> 023 2 5
> 023 4 6
> 023 5 7
> 412 2 5
> 412 3 4
> 412 4 6
> 412 7 9
> 220 5 7
> 220 4 8
> 220 9 8
> ......
>
Now I want to compute the
2012 May 07
1
estimating survival times with glmnet and coxph
Dear all,
I am using glmnet (Coxnet) for building a Cox Model and
to make actual prediction, i.e. to estimate the survival function S(t,Xn) for a
new subject Xn. If I am not mistaken, glmnet (coxnet) returns beta, beta*X and
exp(beta*X), which on its own cannot generate S(t,Xn). We miss baseline
survival function So(t).
Below is my code which takes beta coefficients from
glmnet and creates coxph
2006 Oct 02
1
multilevel factor model in lmer
Hello --
I am curious if lmer can be used to fit a multilevel factor model such as a
two-parameter item response model. The one parameter model is
straightforward. A two-factor model requires a set of factor loadings
multiplying a single random effect. For example, a logit model for the ith
subject responding correctly to the jth item (j=1,..,J) is
logit[p(ij)] = a1*item1(i) + ... + aJ *
2007 Oct 29
1
How to test combined effects?
Suppose I have a mixed-effects model where yij is the jth sample for
the ith subject:
yij= beta0 + beta1(age) + beta2(age^2) + beta3(age^3) + beta4(IQ) +
beta5(IQ^2) + beta6(age*IQ) + beta7(age^2*IQ) + beta8(age^3 *IQ)
+random intercepti + eij
In R how can I get an F test against the null hypothesis of
beta6=beta7=beta8=0? In SAS I can run something like contrast age*IQ
1,
2002 Dec 06
6
fast code
Hello,
I have two vectors x1 and x2 both in increasing order.
I want to select the x1[j]th entry which is the max min of the x2[i]th
entry. I can do this using if and for statements but is there a quick way
to do it without running a loop?
Thank you in advance,
Pantelis
2012 Feb 23
5
cor() on sets of vectors
suppose I have two sets of vectors: x1,x2,...,xN and y1,y2,...,yN.
I want N correlations: cor(x1,y1), cor(x2,y2), ..., cor(xN,yN).
my sets of vectors are arranged as data frames x & y (vector=column):
x <- data.frame(a=rnorm(10),b=rnorm(10),c=rnorm(10))
y <- data.frame(d=rnorm(10),e=rnorm(10),f=rnorm(10))
cor(x,y) returns a _matrix_ of all pairwise correlations:
cor(x,y)
2004 Apr 07
1
eigenvalues for a sparse matrix
Hi,
I have the following problem. It has two parts.
1. I need to calculate the stationary probabilities of a Markov chain,
eg if the transition matrix is P, I need x such that
xP = x
in other words, the left eigenvectors of P which have an eigenvalue of
one.
Currently I am using eigen(t(P)) and then pick out the vectors I need.
However, this seems to be an overkill (I only need a single
2004 Sep 29
2
Approximate a f(x,y)
Hi all,
Running simulations, I'm generating market response to 2 factors X&Y..
There is no closed form for the market response.. The results are store in a
matrix Z(X <- seq(.02,.98,.02), Y <- seq(.01,.19,.01))..
For optmization purpose I need to approximate the values for any factor X in
0,02-0,98 and Y in 0,01-0,19
How can I do it ?
For one factor : Xn-1 < x <= Xn
2011 Mar 25
4
read.xls -> rotate data.frame
Hi to all,
how could I to rotate automatically a data sheet which was imported by
read.xls?
x1 x2 x3 .... xn
y1 1 4 7 ... xn/y1
y2 2 5 8 .... xn/y2
y3 3 6 9 ....xn/y2
yn ... ... ... Xn/Yn
to
y1 y2 y3 .... yn
x1 1 2 3 ..... Yn/x1
x2 4 5 6 .... Yn/x2
x3 7 8 9 .... Yn/x2
xn ... ... ... ..... Yn/xn
Kind regards Knut
2000 May 02
2
Variable names in model formula
At 10:37 PM 5/1/00 -0400, E. S. Venkatraman wrote:
>I have the following problem. I have survival data (time, status) along
>with several covariates (X1, X2,..., Xn). I want to fit a Cox model for
>each of the covariate (univariately) and obtain the fitted probability of
>survival at a fixed time point t0 and covariate value Xi0. I tried to do
>this in a for loop where the index
2004 Nov 03
3
fold right - recursive list (vector) operators
The programming language mosml comes with foldr that 'accumulates' a
function f over a list [x1,x2,...,xn] with initial value b as follows
foldr f b [x1,x2,...,xn] = f(x1,...,f(xn-1,f(xn,b))...)
Observe that "list" should have same elements so in R terminology it would
perhaps be appropriate to say that the accumulation takes place over a
'vector'.
I wonder if R
2012 Apr 16
1
eval a SYMSXP from C
Can someone offer some advice on how to properly evaluate a SYMSXP
from a .Call ?
I have the following in R:
variable xn, with an attribute "mu" which references the variable mu
in the global environment.
I know "references" is a loose term; mu was defined in this fashion as
a way to implement deferred binding:
foo <- function(x,mu) {
attr(x,"mu") <-
2017 Dec 03
5
Rcpp, dyn.load and C++ problems
Hi,
I have written a small C++ function and compile it.
However in R I can't see the function I have defined in C++.
I have read some web-pages about Rcpp and C++ but it is a bit confusion
for me.
Anyway,
This is the C++-code:
#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export]]
List compute_values_cpp(int totalPoints = 1e5, double angle_increment =
0.01, int radius =