Adding labels on curves in glmnet plot in R

Question

I am using glmnet package to get following graph from mtcars dataset (regression of mpg on other variables):

library(glmnet)
fit = glmnet(as.matrix(mtcars[-1]), mtcars[,1])
plot(fit, xvar='lambda')

How can I add names of variables to each curve, either at beginning of each curve or at its maximal y point (maximum away from x-axis)? I tried and I can add legend as usual but not labels on each curve or at its start. Thanks for your help.

Answer 1

As the labels are hard coded it is perhaps easier to write a quick function. This is just a quick shot, so can be changed to be more thorough. I would also note that when using the lasso there are normally a lot of variables so there will be a lot of overlap of the labels (as seen in your small example)

lbs_fun <- function(fit, ...) {
        L <- length(fit$lambda)
        x <- log(fit$lambda[L])
        y <- fit$beta[, L]
        labs <- names(y)
        text(x, y, labels=labs, ...)
}

# plot
plot(fit, xvar="lambda")

# label
lbs_fun(fit)