adding PCA ellipses on ggplot2

Question

[demoraesdiogo2017]

Hello I have used the following code to generate a PCA graph of my data

library(ggplot2)

pca.data <- data.frame(Sample=rownames(pca$x),
                       X=pca$x[,1],
                       Y=pca$x[,2])
pca.data

ggplot(data=pca.data, aes(x=X, y=Y, label=Sample)) +
  geom_text() +
  xlab(paste("PC1 - ", pca.var.per[1], "%", sep="")) +
  ylab(paste("PC2 - ", pca.var.per[2], "%", sep="")) +
  theme_bw() +
  ggtitle("Cancer studies PCA")

But was unable to add ellipses to it. Most tutorials I have seem have used ggbiplot for ellipses, and for some reason I'm unable to download this package (it says it doesn't exist).

What can I do?

[Joe]

Are you sure it says the package doesn’t exist, or just isn’t available for your R version etc?

[h.mon]

How are you trying to install ggplot2? Could you also post the results of sessionInfo()?

[Kevin Blighe]

You can just install the development version straight from GitHub:

devtools::install_github("vqv/ggbiplot")

Downloading GitHub repo vqv/ggbiplot@master
from URL https://api.github.com/repos/vqv/ggbiplot/zipball/master
Installing ggbiplot
* installing *source* package ‘ggbiplot’ ...
** R
** data
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
** building package indices
** testing if installed package can be loaded
* DONE (ggbiplot)

.

library(ggbiplot)
Carregando pacotes exigidos: ggplot2
Carregando pacotes exigidos: plyr
Carregando pacotes exigidos: scales
Carregando pacotes exigidos: grid

.

?ggbiplot
ggbiplot               package:ggbiplot                R Documentation

Biplot for Principal Components using ggplot2

Description:

     Biplot for Principal Components using ggplot2

Usage:

       ggbiplot(pcobj, choices = 1:2, scale = 1, pc.biplot =
       TRUE, obs.scale = 1 - scale, var.scale = scale, groups =
       NULL, ellipse = FALSE, ellipse.prob = 0.68, labels =
       NULL, labels.size = 3, alpha = 1, var.axes = TRUE, circle
       = FALSE, circle.prob = 0.69, varname.size = 3,
       varname.adjust = 1.5, varname.abbrev = FALSE, ...)

Arguments:

   pcobj: an object returned by prcomp() or princomp()

 choices: which PCs to plot

   scale: covariance biplot (scale = 1), form biplot (scale = 0). When
          scale = 1, the inner product between the variables
          approximates the covariance and the distance between the
          points approximates the Mahalanobis distance.

obs.scale: scale factor to apply to observations

var.scale: scale factor to apply to variables

pc.biplot: for compatibility with biplot.princomp()

  groups: optional factor variable indicating the groups that the
          observations belong to. If provided the points will be
          colored according to groups

 ellipse: draw a normal data ellipse for each group?