Following my introduction to PCA, I will demonstrate how to apply and visualize PCA in R. There are many packages and functions that can apply PCA in R. In this post I will use the function `prcomp`

from the `stats`

package. I will also show how to visualize PCA in R using Base R graphics. However, my favorite visualization function for PCA is `ggbiplot`

, which is implemented by Vince Q. Vu and available on github. Please, let me know if you have better ways to visualize PCA in R.

** Computing the Principal Components (PC) **

I will use the classical `iris`

dataset for the demonstration. The data contain four continuous variables which corresponds to physical measures of flowers and a categorical variable describing the flowersâ€™ species.

We will apply PCA to the four continuous variables and use the categorical variable to visualize the PCs later. Notice that inâ€¦

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