turtorials of PCA with R

http://gettinggeneticsdone.blogspot.com/2010/05/tutorial-principle-components-analysis.html

http://programming-r-pro-bro.blogspot.com/2011/10/principal-component-analysis-use.html

http://programming-r-pro-bro.blogspot.com/2011/10/principal-component-analysis-use_23.html