Formatting and manipulating a plot from the R package "hexbin"

Question

I generate a plot using the package hexbin:

# install.packages("hexbin", dependencies=T)
library(hexbin)


set.seed(1234)
x <- rnorm(1e6)
y <- rnorm(1e6)
hbin <- hexbin(
  x   = x
  , y = y
  , xbin = 50
  , xlab = expression(alpha)
  , ylab = expression(beta)
)


## Using plot method for hexbin objects:
plot(hbin, style = "nested.lattice")

abline(h=0)

This seems to generate an S4 object (hbin), which I then plot using plot. Now I'd like to add a horizontal line to that plot using abline, but unfortunately this gives the error:

plot.new has not yet been called

I have also no idea, how I can manipulate e.g. the position of the axis labels (alpha and beta are within the numbers), change the position of the legend, etc.

I'm familiar with OOP, but so far I could not find out how plot() handles the object (does it call certain methods of the object?) and how I can manipulate the resulting plot.

Why can't I simply draw a line onto the plot?

How can I manipulate axis labels?

Answer 1

Use lattice version of hex bin - hexbinplot(). With panel you can add your line, and with style you can choose different ways of visualizing hexagons. Check help for hexbinplot for more.

library(hexbin)
library(lattice)
x <- rnorm(1e6)
y <- rnorm(1e6)
hexbinplot(x ~ y, aspect = 1, bins=50, 
           xlab = expression(alpha), ylab = expression(beta), 
           style = "nested.centroids",
           panel = function(...) {
             panel.hexbinplot(...)
             panel.abline(h=0)
             })

Answer 2

hexbin uses grid graphics, not base. There is a similar function, grid.abline, which can draw lines on plots by specifying a slope and intercept, but the co-ordinate system used is confusing:

grid.abline(325,0)

gets approximately what you want, but the intercept here was found by eye.

You will have more luck using ggplot2:

library(ggplot2)
ggplot(data,aes(x=alpha,y=beta)) + geom_hex(bins=10) + geom_hline(yintercept=0.5)