Displaying 20 results from an estimated 3000 matches similar to: "PCA"
2003 Apr 21
2
name of arrays
Hello,
I computed acf() and have an array as output. now I would like to have
only one matrix or data frame (not yet familiar with the nomenclature)
extracted from this array. or even only the first row of each matrix.
the first part of my data "test" is called
$acf
,1
, , 1 , , 2
1, , ... ...
2, , .. ...
I tried several names but nothing wants to work, I only
2003 Apr 03
1
ts function
hello
I read "Practical Time Series" (Gareth Janacek; 2001) and they presented
e.g the
smoothing functions msmooth(x,k) or the bivariate function
crosscorr(x,y,k),
but both didn't work on my machine. I only load the ts library, is
another
library necessary or did this function change since 2001? Is there a
more recent and detailed manual for ts?
thanks, cheers Martin
--
Martin
2003 Apr 30
1
Interactive Input Problem
Hi,
I built and installed R-base-1.7.0 on SuSE 8.2 without any problems, but the
interactive R interpreter, has problems with cursor movement:
> ls()
character(0)
> ^[[A^[[B^[[D^[[C^[[A^[[D^[[C^[[B^[[D^[[A
These ugly characters are produced by the arrow keys. Does anyone know how to
fix that problem?
Ciao
Sebastian
2003 Apr 30
2
acf() with two df?
Hello,
I have two dataframes, one with a time series of variables and another
one with biological data of each plot. the column names correspond to
each other
plot1 plot 2.......
1983 ... ....
1984 ... ....
...
and
plot 1 plot2
1 ... ...
2
is it somehow possible to use acf() with two data frames and get a p
values for the whole correaltion of these
2010 Apr 02
2
Biplot for PCA using labdsv package
Hi everyone,
I am doing PCA with labdsv package. I was trying to create a biplot graphs
in order to observe arrows related to my variables. However when I run the
script for this graph, the console just keep saying:
*Error in nrow(y) : element 1 is empty;
the part of the args list of 'dim' being evaluated was:
(x)*
could please someone tell me what this means? what i am doing
2010 Jun 30
3
Factor Loadings in Vegan's PCA
Hi all,
I am using the vegan package to run a prcincipal components analysis
on forest structural variables (tree density, basal area, average
height, regeneration density) in R.
However, I could not find out how to extract factor loadings
(correlations of each variable with each pca axis), as is straightforwar
in princomp.
Do anyone know how to do that?
Moreover, do anyone knows
2005 Mar 26
5
PCA - princomp can only be used with more units than variables
Hi all:
I am trying to do PCA on the following matrix.
N1 N2 A1 A2 B1 B2
gene_a 90 110 190 210 290 310
gene_b 190 210 390 410 590 610
gene_c 90 110 110 90 120 80
gene_d 200 100 400 90 600 200
>dataf<-read.table("matrix")
>
2009 Feb 13
4
PCA functions
Hi All, would appreciate an answer on this if you have a moment;
Is there a function (before I try and write it !) that allows the input of a
covariance or correlation matrix to calculate PCA, rather than the actual
data as in princomp()
Regards
Glenn
[[alternative HTML version deleted]]
2004 Jul 14
2
PCA in R
Hello,
I'm attempting to run a PCA on an example data set. I ran it
just fine, but I don't know how to few the output? I listed what the
variable got stored in it, but I don't know how I can get anything else out
of it. Are there other ways to view the results?
Also, I'm confused about the last line "6 variables and 8 observations"
Aren't the rows the
2008 May 14
1
PCA in Microarrays
Dear useRs:
I'm not sure if it's the correct place to ask but I'll try it out. I've been
reading about how to perform Principal Component Analysis (PCA) in
microarrays (see [1]) and there's something that I don't get it. Basically
it's related with performing PCA over data sets which number of variables is
greater than the number of samples. For example in the paper
2008 Jul 01
2
PCA : Error in eigen(cv,
Hi all,
I am doing bootstrap on a distance matrix, in which samples have been
drawn with replacement. After that I do PCA on a resulted matrix, and
these 2 steps are repeated 1000 times.
pca(x) is a vector where I wanted to store all 1000 PCAs; and x is from
1 to 1000
SampleD is a new matrix after resampling;
I am getting the following error message, which I don't understand:
....
2008 Jan 04
1
PCA error: svd(x, nu=0) infinite or missing values
Hi,
I am trying to do a PCA on my data but I keep getting the error message
svd(x, nu=0) infinite or missing values
>From the messages posted on the subject, I understand that the NAs in my
data might be the problem, but I thought na.omit would take care of that.
Less than 5% of my cells are missing data. However, the NAs are not
regularly distributed across my matrix: certain cases and
2009 Jan 13
1
PCA loadings differ vastly!
hi, I have two questions:
#first (SPSS vs. R):
I just compared the output of different PCA routines in R (pca, prcomp,
princomp) with results from SPSS. the loadings of the variables differ
vastly! in SPSS the variables load constantly higher than in R.
I made sure that both progr. use the correlation matrix as basis. I
found the same problem with rotated values (varimax rotation and rtex=T
2005 Jun 22
2
PCA and MDS
Dear All,
I am not familar with R. I want to use PCA (principal components
analysis) and MDS (multidimensional scaling). Can someone tell me
which R package I should use for PCA and MDS? I appreciate your help
in advance.
Ray
2008 Jun 17
4
PCA analysis
Hi,
I have a problem with making PCA plots that are readable.
I would like to set different sympols instead of the numbers of my samples or their names, that I get plotted (xlabs).
How is this possible? With points, i donĀ“t seem to get the right data plotted onto the PCA plot, as I do not quite understand from where it is taken. I dont know how to
plot the correct columns of the prcomp
2012 Oct 19
1
factor score from PCA
Hi everyone,
I am trying to get the factor score for each individual case from a principal component analysis, as I understand, both princomp() and prcomp() can not produce this factor score, the principal() in psych package has this option: scores=T, but after running the code, I could not figure out how to show the factor score results. Here is my code, could anyone give me some advice please?
2008 Sep 09
4
PCA and % variance explained
After doing a PCA using princomp, how do you view how much each component
contributes to variance in the dataset. I'm still quite new to the theory of
PCA - I have a little idea about eigenvectors and eigenvalues (these
determine the variance explained?). Are the eigenvalues related to loadings
in R?
Thanks,
Paul
--
View this message in context:
2005 Jul 08
2
extract prop. of. var in pca
Dear R-helpers,
Using the package Lattice, I performed a PCA.
For example
pca.summary <- summary(pc.cr <- princomp(USArrests, cor = TRUE))
The Output of "pca.summary" looks as follows:
Importance of components:
Comp.1 Comp.2 Comp.3 Comp.4
Standard deviation 1.5748783 0.9948694 0.5971291 0.41644938
Proportion of Variance 0.6200604
2004 May 10
1
environmental data as vector in PCA plots
Hi,
I want to include a vector representing the sites - environmental data
correlation in a PCA.
I currently use prcomp (no scaling) to perform the PCA, and envfit to
retrieve the coordinates of the environmental data vector. However, the
vector length is different from the one obtained in CAnoco when performing
a species - environmental biplot (scaling -2). How can I scale the vector
in order to
2008 Jul 03
2
PCA on image data
Dear R users,
i would like to apply a PCA on image data for data reduction.
The image data is available as three matrices for the
RGB values. At the moment i use
x <- data.frame(R,G,B)#convert image data to data frame
pca<-princomp(x,retx = TRUE)
This is working so far.
>From this results then i want to create a new matrix
from the first (second..) principal component. Here i stuck.