Re: [R] PCA and % variance explained

2008-09-10 Thread Gad Abraham 

pgseye wrote:

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?


You can plot the princomp object using screeplot() and you can get the 
percentage of explained variance from the princomp object p using

p$sdev^2 / sum(p$sdev^2)


--
Gad Abraham
Dept. CSSE and NICTA
The University of Melbourne
Parkville 3010, Victoria, Australia
email: [EMAIL PROTECTED]
web: http://www.csse.unimelb.edu.au/~gabraham

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Re: [R] PCA and % variance explained

2008-09-10 Thread pgseye 

Thanks everyone,

Paul


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[R] PCA and % variance explained

2008-09-09 Thread pgseye 

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: 
http://www.nabble.com/PCA-and---variance-explained-tp19388970p19388970.html
Sent from the R help mailing list archive at Nabble.com.

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Re: [R] PCA and % variance explained

2008-09-09 Thread ngottlieb 
I did PCA stuff years there is a thing that is called a scree score 
Which will give an indication of the number of PCA's and the variance
explained.

Might want to web search on scree score and PCA.



-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of pgseye
Sent: Tuesday, September 09, 2008 5:39 AM
To: r-help@r-project.org
Subject: [R] 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:
http://www.nabble.com/PCA-and---variance-explained-tp19388970p19388970.h
tml
Sent from the R help mailing list archive at Nabble.com.

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