[R] PCA - scores

[William Revelle]

Shari,
   Josh partly answered your question, but his example did not include 
rotation because he took out just one factor.

Try:

require(psych)
mt.pc <- principal(mtcars,3,scores=TRUE)   #this gives you the 
varimax rotated first 3 principal components
#pc.scores <- mt.pc$scores     #here are the scores

biplot(mt.pc)    #show the data as well as the principal components in a biplot



Bill


At 5:15 PM -0800 3/3/11, Joshua Wiley wrote:
>Hi Shari,
>
>Yes, please look at the documentation for principal.  You can access
>this (assuming you have loaded psych) by typing at the console:
>
>?principal
>
>note the logical argument "scores".
>
>Here is a small example:
>
>##############################
>require(psych)
>require(GPArotation)
>
>dat <- principal(mtcars[, c("mpg", "hp", "wt")], nfactors = 1,
>   rotate = "oblimin", scores = TRUE)
>
>dat$scores
>##############################
>
>Cheerio,
>
>Josh
>
>On Thu, Mar 3, 2011 at 1:02 PM, Shari Clare <sclare at ualberta.ca> wrote:
>>  I am running a PCA, but would like to rotate my data and limit the
>>  number of factors that are analyzed.  I can do this using the
>>  "principal" command from the psych package [principal(my.data,
>>  nfactors=3,rotate="varimax")], but the issue is that this does not
>>  report scores for the Principal Components the way "princomp" does.
>>
>>  My question is:
>>
>>  Can you get an output of scores using "principal" OR, is there a way
>>  to limit the number of factors that are included when you use
>>  "princomp"?
>>
>>  Thanks,
>>  Shari Clare
>>
>>  PhD Candidate
>>  Department of Renewable Resources
>>  University of Alberta
>>  sclare at ualberta.ca
>>  780-492-2540
>>
>>
>>
>>
>>
>>
>>
>>
>>         [[alternative HTML version deleted]]
>>
>>  ______________________________________________
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>>  https://stat.ethz.ch/mailman/listinfo/r-help
>>  PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>>  and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
>--
>Joshua Wiley
>Ph.D. Student, Health Psychology
>University of California, Los Angeles
>http://www.joshuawiley.com/
>
>______________________________________________
>R-help at r-project.org mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.