factor analysis (pca): how to get the 'communalities'?
Wolfgang Lindner wrote:
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'Misc-1.0.R ;-) ..
Helpful could be to give some examples of calling your functions.
Please excuse me, if the following questions are *too* off-topic, 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 left-handside 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?
It's not necessary for this particular name to put in in quotes, but you
can put any name in quotes:
"x" <- 5
x
Here you must quote (BAD idea to choose such names!, NOT
recommended!!!):
"x 1" <- 5
get("x 1")
- How is "cov.cor" then called? "cov.cor"(..) or cov.cor(..) or ?
Both ways are possible in this case.
Q2. Please, can someone give me a pointer where this feature is described.
R FAQ 7.16 - 2. item in the enumeration.
Finally I want to thank the list for this thread.
Uwe Ligges