title: Principal Component Analysis in r using prcomp()
body: <p>My data is a [478 x 4200] matrix. I am considering 4200 elements as components and I want to reduce the number of components that I need to take care of.
  I used prcomp() and somehow it always returns 478 principal components even though I transpose the matrix. As far as I understand prcomp() uses columns as  components. I think I should get 4200 principle components.
  I can do it manually by computing all the matrices that I need, but I want to check with this function. </p>