[R] factor analysis (pca): how to get the 'communalities'?
Wolfgang Lindner
LindnerW at tonline.de
Sat Jan 4 12:52:03 CET 2003
Brett Magill schrieb:
 If interested, on my web site I have code to do factor analysis by PC. Does
 exactly as below, but a nice wrapper to print methods, rotations, sorting, and
 other conveniences.

 home.earthlink.net/~bmagill/MyMisc.html

 The relevant code snipets are "prinfact", "plot.pfa", and "print.pfa", along
 with the other required functions as indiciated on the web site.
Dear Brett,
thanks very much for supplying your code. It's really illuminating.
Now, let me quote you
'When I have time, I will document them and wrap them up into a package that
can be installed.'
I hope you will find some time to prepare 'Your'Misc1.0.R ;) ..
Helpful could be to give some examples of calling your functions.
Please excuse me, if the following questions are *too* offtopic, but I found it
interesting. In inspecting your code I came across an R feature, I could not
find in the online manuals:
Q1. Looking at the lefthandside in your function def:
"cov.cor" < function ( covmat ) {
sdev < diag ( sqrt ( diag ( covmat ) ) )
solve(sdev) %*% covmat %*% t(solve(sdev)) }
^ ^
 
? ?
 *Why* is the (identifier) function name cov.cor included in question marks?
 How is "cov.cor" then called? "cov.cor"(..) or cov.cor(..) or ?
Q2. Please, can someone give me a pointer where this feature is described.
Finally I want to thank the list for this thread.
Wolfgang

Wolfgang Lindner Lindner at math.uniduisburg.de
GerhardMercatorUniversitaet Duisburg Tel: +49 0203 3791326
Fakultaet 4  Naturwissenschaften Fax: +49 0203 3792528
Institut fuer Mathematik, LE 424
Lotharstr. 65
D 47048 Duisburg (Germany)
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