How to install install_github function on R?

Question

I am trying to use a github package from a worked example. I used the suggested methods

here to get the install-github working

library(devtools)
library(httr)
set_config(config(ssl_verifypeer = 0L))
install.packages("install_github")
install_github("ggbiplot", "vqv")

I get a warning that redirects me to the R website install page, and then error Error in parse_repo_spec(repo) : Invalid git repo specification: 'ggbiplot'

Ultimately, I want to run this piece of code

# Load data
data(iris)
log.ir <- log(iris[, 1:4])
ir.species <- iris[, 5]

#PCA
ir.pca <- prcomp(log.ir,
                 center = TRUE,
                 scale. = TRUE) 
#Plot
g <- ggbiplot(ir.pca, obs.scale = 1, var.scale = 1, 
              groups = ir.species, ellipse = TRUE, 
              circle = TRUE)
g <- g + scale_color_discrete(name = '')
g <- g + theme(legend.direction = 'horizontal', 
               legend.position = 'top')
print(g)

Answer 1

You need the user/repo syntax to specify the repo, since there are multiple packages called ggbiplot on GitHub - the R package has 157 forks and you have to tell R which one you want:

library(devtools)

install_github('vqv/ggbiplot')
#> Downloading GitHub repo vqv/ggbiplot@HEAD

library(ggbiplot)

Now we can run your code:

data(iris)
log.ir <- log(iris[, 1:4])
ir.species <- iris[, 5]

#PCA
ir.pca <- prcomp(log.ir,
                 center = TRUE,
                 scale. = TRUE) 
#Plot
g <- ggbiplot(ir.pca, obs.scale = 1, var.scale = 1, 
              groups = ir.species, ellipse = TRUE, 
              circle = TRUE)
g <- g + scale_color_discrete(name = '')
g <- g + theme(legend.direction = 'horizontal', 
               legend.position = 'top')
print(g)