PCA problem in R
R.P.Clement at westminster.ac.uk wrote:
Hi. I have two comments on this. Quoting Prof Brian Ripley <ripley at stats.ox.ac.uk>:
On Sat, 13 Aug 2005, Alan Zhao wrote:
When I have more variables than units, say a 195*10896 matrix which has 10896 variables and 195 samples. prcomp will give only 195 principal components. I checked in the help, but there is no explanation that why this happen.
There is not even a definition of a PC in the help. Did you read the references? This is what they are given for!
I don't know if it's too simple and introductory for the OP, but I quite like Lindsay Smith's intro to PCA. http://www.cs.otago.ac.nz/cosc453/student_tutorials/principal_components.pdf
It is a very good tutorial. Thank you very much for your help. Sincerely, Zheng Zhao Aug-14-2005