Displaying 20 results from an estimated 5000 matches similar to: "Centering (e.g. on prcomp)"
2012 Jun 28
1
plot.prcomp() call/eval
Hi!
I am getting a lot of numbers in the background of the pca screeplots if i use call("plot") and eval(somecall).
Til now, creating the calls and plotting later on this way worked fine. Example:
pcaI<-prcomp(iris[,1:4])
plot(pcaI)
x<-call("plot",pcaI)
eval(x)
Anyone got an idea how i can avoid that? (also it might take a second or so for the numbers to appear,
2012 Nov 15
1
Can't see what i did wrong..
with
pred.pca<-predict(splits[[i]]$pca,trainingData at samples)[,1:nPCs]
dframe<-as.data.frame(cbind(pred.pca,class=isExplosive(trainingData,2)));
results[[i]]$classifier<-ksvm(class~.,data=dframe,scaled=T,kernel="polydot",type="C-svc",
C=C,kpar=list(degree=degree,scale=scale,offset=offset),prob.model=T)
and a degree of 5 i get an error of 0 reported by the ksvm
2009 Mar 08
2
prcomp(X,center=F) ??
I do not understand, from a PCA point of view, the option center=F
of prcomp()
According to the help page, the calculation in prcomp() "is done by a
singular value decomposition of the (centered and possibly scaled) data
matrix, not by using eigen on the covariance matrix" (as it's done by
princomp()) .
"This is generally the preferred method for numerical accuracy"
2012 Mar 28
2
Making Knitr work
Might not be the best place to ask, but i could get lucky..
I have setup an eclipse environment to write sweave files lately and wanted to switch to knitr. I could get it to work on easy files, but my earlier written sweave file fails to be knit properly.
Here is the error message:
Quitting from lines 273-276: Error in setwd(base.dir) : kann Arbeitsverzeichnis nicht wechseln (it says: cannot
2012 Aug 02
4
Subseting
Hi everyone
I have banking data set in long format with 4 columns.One of these columns
is bank name which consist of 49 banks and I want the data for only 40
banks out of these 49
so can anyone help me on how to get this 40 banks data
My data looks like
Year Name totalliabilties assets
1990 a 90 10
1991 a 89 48
1992 a 87
2009 Oct 19
2
What is the difference between prcomp and princomp?
Some webpage has described prcomp and princomp, but I am still not
quite sure what the major difference between them is. Can they be used
interchangeably?
In help, it says
'princomp' only handles so-called R-mode PCA, that is feature
extraction of variables. If a data matrix is supplied (possibly
via a formula) it is required that there are at least as many
units as
2006 Jun 26
1
princomp and prcomp confusion
When I look through archives at
https://stat.ethz.ch/pipermail/r-help/2003-October/040525.html
I see this:
Liaw, Andy wrote:
>In the `Detail' section of ?princomp:
>
>princomp only handles so-called Q-mode PCA, that is feature extraction of
>variables. If a data matrix is supplied (possibly via a formula) it is
>required that there are at least as many units as variables. For
2012 Dec 20
2
Filling Lists or Arrays of variable dimensions
Following problem:
Say you have a bunch of parameters and want to produce results for all combinations of those:
height<-c("high","low")
width<-c("slim","wide")
then what i used to do was something like this:
l<-list()
for(h in height){
l[[h]]<-list()
for(w in width){
l[[h]][[w]] <- doSomething()
}
}
Now those parameters aren't
2012 Jul 10
2
define stuff to be only usable in the same file
Hello R-Help!
I've looked around and have not found:
A simple(short) way to hide functions and variables from the global environment. What i want is for a few of them to only be accessable from the scriptfile they're in. I probably could do fun things with environments , but that seems quite a hassle.
As example: I have a file that gets me stuff from the database and creates an R object
2012 Oct 09
2
append for .Rdata?
Can i somehow append objects to an .Rdata file?
I didn't see an option for it in the save() method.
dump() won't work since i have s4 objects in there.
2012 Oct 10
2
Strange email i'm getting whenever i post to the list
From: ?????? <NAVER-MAILER at naver.com>
Subject: [???? ??] envy721c at naver.cobSDsnLzroZwg66mU7J287J20IOyghOyGoeuQmOyngCDrqrvtlojsig==teuLiOuLpC4=
The only plain english in the message is that the mail was denied by the receiver
Anyone else getting this?
2012 Apr 27
2
Where would i put feature requests for a library?
Hi!
If i found a problem with the code of one of the libraries (not core), or, in my current case, would wish something minor changed for convenience, where can i get contact? Can i put it in the "official" bug repository?
(Problem discription for anyone interested:
Why call the default function kpca for a matrix with kpar=list(sigma=0.2), instead of putting this default sigma into the
2006 Mar 25
1
Suggest patch for princomp.formula and prcomp.formula
Dear all,
perhaps I am using princomp.formula and prcomp.formula in a way that
is not documented to work, but then the documentation just says:
formula: a formula with no response variable.
Thus, to avoid a lot of typing, it would be nice if one could use '.'
and '-' in the formula, e.g.
> library(DAAG)
> res <- prcomp(~ . - case - site - Pop - sex, possum)
2006 Nov 16
1
Problems with principal components analysis PCA with prcomp
Dear friends,
I am beginning to use R software in my academic research and I'm having some
problems regarding the use of PCA.
I have a table with 24445 rows and 9 columns, and I used the function
prcomp() to do the analysis.
Working with an example?:
x<-read.table("test.txt", header=T)
row.names(x)<-x[,1]
x<-x[,-1]
require(stats)
pca<-prcomp(x, scale=T)
names(pca)
##
2012 May 07
3
How to plot PCA output?
I have a decent sized matrix (36 x 11,000) that I have preformed a PCA on
with prcomp(), but due to the large number of variables I can't plot the
result with biplot(). How else can I plot the PCA output?
I tried posting this before, but got no responses so I'm trying again.
Surely this is a common problem, but I can't find a solution with google?
The University of Dundee is a
2009 Mar 10
1
Using napredict in prcomp
Hello all,
I wish to compute site scores using PCA (prcomp) on a matrix with
missing values, for example:
Drain Slope OrgL
a 4 1 NA
b 2.5 39 6
c 6 8 45
d 3 9 12
e 3 16 4
...
Where a,b... are sites.
The command
> pca<-prcomp(~ Drain + Slope + OrgL, data = t, center = TRUE, scale =
TRUE, na.action=na.exclude)
works great, and from
2012 Mar 26
1
normalization of multi-value string variable
Hi All,
I need to normalize/scale string variable which represents interests of customers (e.g., 'cycling, rollerblading, swimming' etc).
Does anybody know how to do this, I want then use it along with other numeric variables for SVM classification.
Appreciate for any advice.
-Alex
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2012 Apr 03
1
e1071 tune.control() random parameter
I'm not sure what the parameter specifies:
random
if an integer value is specified, random parameter vectors are drawn from the parameter space.
What are the parameter vectors and what is the parameter space? What means drawn?
greetings
Jessi
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2012 Apr 26
1
kernlab kpca code
Hi!
how do i get to the source code of kpca or even better predict.kpca(which it tells me doesn't exist but should) ?
(And if anyone has too much time:
Now if i got that right, the @pcv attribute consists of the principal components, and for kpca, these are defined as projections of some random point x, which was transformed into the other feature space -> f(x), projected onto the actual
2008 Feb 10
1
prcomp vs. princomp vs fast.prcomp
Hi R People:
When performing PCA, should I use prcomp, princomp or fast.prcomp, please?
thanks.
Erin
--
Erin Hodgess
Associate Professor
Department of Computer and Mathematical Sciences
University of Houston - Downtown
mailto: erinm.hodgess at gmail.com