Question

When I draw grid lines on a plot using abline() the grid lines are drawn over the data.

Is there a way to draw the abline() lines behind the data? I feel this would look better.

Example:

x <- seq(0, 10)
y <- x
plot(x, y, col = 'red', type = 'o', lwd = 3, pch = 15)
abline(h = seq(0, 10, .5), col = 'lightgray', lty = 3)
abline(v = seq(0, 10, .5), col = 'lightgray', lty = 3)

The plot produced has the gray grid lines going over the data (red line). I would like the red line to be on top of the gray lines.

Answer 1

The panel.first argument of plot() can take a list or vector of functions so you can put your abline() calls in there.

plot(1:4, panel.first = 
       c(abline(h = 1:4, lty = 2, col = 'grey') 
        ,abline(v = 1:4, lty = 2, col = 'grey')))