Re: [R] PCA problem in R

From: Alan Zhao <alanzhao_at_gmail.com>
Date: Mon 15 Aug 2005 - 10:57:52 EST

R.P.Clement@westminster.ac.uk wrote:
> Hi. I have two comments on this.
>
> Quoting Prof Brian Ripley <ripley@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



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