Displaying 20 results from an estimated 1000 matches similar to: "Erratic behaviour of sammon()"
2006 Jan 30
1
Varying results of sammon(), for the same data set
Hello,
I have a data set on which I run the sammon algorithm as follows:
library(MASS)
data = read.table('problemforr.dat')
y = cmdscale(data, add=TRUE)
s = sammon(data, y$points)
(In case it should be relevant, I make the data available at
http://idi.ntnu.no/~edsberg/problemforr.dat)
With R 2.2.1 on Debian Sid I always get one of two solutions (stress
1.74288 after 10 iterations or
2004 Jun 14
1
error running sammon
Hello,
I am inputing a 17 x 17 symetric matrix to sammon. The matrix is a co-occurance matrix with no missing data. If this is at all relevant, running hclust on this matrix works.
> samx <- sammon(q23axproduct)
I receive the following error:
Error in sammon(q23axproduct) : initial configuration must be complete
In addition: Warning messages:
1: some of the first 2 eigenvalues are
2005 Apr 20
4
results from sammon()
Dear all,
I'm trying to get a two dimensional embedding of some data using different
meythods, among which princomp(), cmds(), sammon() and isoMDS(). I have a
problem with sammon() because the coordinates I get are all equal to NA.
What does it mean? Why the method fails in finding the coordinates? Can I do
anything to get some meaningful results?
Thank you very much
Domenico
2007 Aug 23
0
indexing and regression testing
Dear all,
It was a pleasure to meet you at Iowa State University. Two days ago I submitted two experimental packages to CRAN (hope it will be there soon):
rindex: quick indexing of large objects (currently only character, see ?index)
regtest: some first support for automated regression testing (heavily used in \dontshow{} section of ?index)
With rindex you can for example
i <-
2002 Jul 30
3
Error running sammon() in multiv package
When I try to run the "sammon" function of the multiv package, I always get
this error message:
Error in as.vector(dist(a)) : couldn't find function "dist"
It happens even with example(sammon). I am running R 1.5.0 on Win98 and I
have still installed R 1.4.1 but it doesn't work on the old R version with
the older multiv package either. Is there a problem with the
2009 Jul 27
1
how to use do.call together with cbind and get inside a function
Dear R-helpers:
I have a question related to using do.call to call cbind and get.
#the following works
vec1 <- c(1,2)
vec2 <- c(3,4)
ColNameVec <- c('vec1','vec2')
mat <- do.call("cbind",lapply(ColNameVec,get))
mat
#put code above into a function then it does not work
#before doing so, first remove vec1 and vec2 from global environment
rm(vec1,vec2)
test
2008 Dec 30
2
[LLVMdev] Folding vector instructions
Hello.
Sorry I am not sure this question should go to llvm or mesa3d-dev mailing
list, so I post it to both.
I am writing a llvm backend for a modern graphics processor which has a ISA
very similar to that of Direct 3D.
I am reading the code in Gallium-3D driver in a mesa3d branch, which
converts the shader programs (TGSI tokens) to LLVM IR.
For the shader instruction also found in LLVM IR,
2001 Oct 12
1
MASS: isoMDS and sammon
If tbl is an object of class 'dist', you can do this:
a <- sammon(tbl, k=3)
But you can't do this:
b <- isoMDS(tbl, k=3)
Wouldn't it be sensible to have identical interfaces to sammon()
and isoMDS() ?
I think all that would be needed is to change this:
isoMDS <- function(d, y=cmdscale(d, 2), maxit=50, trace=TRUE)
{
...into this:
isoMDS <-
2004 May 25
1
cor and missing values. Bug?
There seems to be an issue in computing rank correlations with missing
values present. I think this comes from the way rank() function works but
I am not sure how to go about this. Rank function places missing values at
the end by default thus skewing the rank relationship between two vectors:
Example:
R : Copyright 2003, The R Foundation for Statistical Computing
Version 1.8.1 (2003-11-21),
2011 Jun 03
2
Arules: R Crashes when running eclat with tidLists=TRUE
Hello,
I'm using the eclat function of the arules package (1.0-6) for the
identification of frequent itemsets. I need the tidLists, but if I set
in the function tidLists=TRUE R crashes (Windows XP Professional SP3,
32 bit, R version 2.12.1 (2010-12-16), reproducible on two different
computers) with two different error messages or non at all. Minimum
examples are:
library(arules)
2008 May 12
1
lexicographic comparison of two vectors
Is there any built-in way to lexicographically compare two vectors of
the same length in R? The textbook algorithm could be coded as follows:
lex.cmp <- function (vec1,vec2) {
for (j in 1:length(vec1)) {
if (vec1[j] < vec2[j]) { return(-1) }
if (vec1[j] > vec2[j]) { return(1) }
}
return(0)
}
Thanks,
Gabriel
2011 Apr 14
1
nesting multiple for loops
Hi everyone.
I am quite frustrated that this doesn't work, as all the functions within
work fine by themselves. I'd also like any pointers to how to avoid 'for'
loops in my code. I understand it's less than desirable, but I'm still quite
new and use them a lot.
I have a few wide datasets (90 to 120) with long column names, each name
contains a number of different
2008 Dec 30
2
[LLVMdev] [Mesa3d-dev] Folding vector instructions
Alex wrote:
> Hello.
>
> Sorry I am not sure this question should go to llvm or mesa3d-dev mailing
> list, so I post it to both.
>
> I am writing a llvm backend for a modern graphics processor which has a ISA
> very similar to that of Direct 3D.
>
> I am reading the code in Gallium-3D driver in a mesa3d branch, which
> converts the shader programs (TGSI tokens) to
2010 Jul 12
2
findInterval and data resolution
Hello Wise Ones...
I need a clever way around a problem with findInterval. Consider:
vec1 <- 1:10
vec2 <- seq(1, 10, by = 0.1)
x1 <- c(2:3)
a1 <- findInterval(x1, vec1); a1 # example 1
a2 <- findInterval(x1, vec2); a2 # example 2
In the problem I'm working on, vec* may be either integer or numeric, like
vec1 and vec2. I need to remove one or more sections of this vector;
2013 Apr 18
1
vectors with equal values
Hi,
Try:
?vec1<-c(1,1,1,1,1,1,1,1,1)
if(all(vec1==1)) "xxxxxxxxx" else? "yyyyyyyyyyy"
#[1] "xxxxxxxxx"
?vec2<-c(rep(1,4),2)
?if(all(vec2==1)) "xxxxxxxxx" else? "yyyyyyyyyyy"
#[1] "yyyyyyyyyyy"
#or
if(length(unique(vec1))==1) "xxxxxxxxx" else? "yyyyyyyyyyy"
#[1] "xxxxxxxxx"
? if(length(unique(vec2))==1)
2008 Sep 20
1
lower and upper limits in integrate as vectors
Dear R useRs,
i try to integrate the following function for many values
"integrand" <- function(z)
{
return(z * z)
}
i do this with a for-loop
for(i in 2:4)
{
z <- integrate(integrand, i-1, i)$value
cat("z", z, "\n")
}
to speed up the computation for many values i tried vectors
in integrate to do this.
vec1<-1:3
vec2<-2:4
2013 Mar 22
2
A question on function return
Hello again,
Let say I have following user defined function:
fn <- function(x, y) {
Vec1 <- letters[1:6]
Vec2 <- 1:5
return(list(ifelse(x > 0, Vec1, NA), ifelse(y > 0, Vec2, NA)))
}
Now I have following calculation:
> fn(-3, -3)
[[1]]
[1] NA
[[2]]
[1] NA
> fn(3, -3)
[[1]]
[1] "a"
[[2]]
[1] NA
Here I can not understand why in the second case, I get
2004 Jul 09
3
Problem with bwplot
Try factor(vec2) in your bwplot() call.
-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch]On Behalf Of Ernesto Jardim
Sent: Friday, July 09, 2004 9:41 AM
To: Mailing List R
Subject: [R] Problem with bwplot
Hi,
I'm ploting some box-and-whisker plots with bwplot but I'm not getting
any box-and-whiskers ... just dots.
2005 Jun 09
1
Subassignments involving NAs in data frames
I'm seeing some inconsistent behavior when re-assigning values in a data
frame. The first assignment turns all of the 0s in my data frame to 2s,
the second fails to do so.
> df1 <- data.frame(a = c(NA, 0, 3, 4))
> df2 <- data.frame(a = c(NA, 0, 0, 4))
> df1[df1 == 0] <- 2 ## Works
> df2[df2 == 0] <- 2
Error: NAs are not allowed in subscripted assignments
Checking an
2010 Aug 24
3
multiple assignments ?
Simple one, have read and googled, still no luck!
I want to create several empty vectors all of the same length.
I would like multiple empty vectors (vec1, vec2, vec3) and want to create them all in one line.
I've tried
vec1,vec2,vec3 <- vector(length=5)
and
c(vec1,vec2,vec3) <- vector(length=5)
and several other attempts but nothing seems to work ... suggestions?
Thanks
Jim