How do I draw gridlines using abline() that are behind the data?

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

Answer 1

Use plot() to set up the plotting window, but use type = "n" to not plot any data. Then do your abline() calls, or use grid(), and then plot the data using whatever low-level function is appropriate (here points() is fine).

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

or

## using `grid()`
plot(x, y, type = "n")
grid()
points(x, y, col = 'red', type = 'o', lwd = 3, pch = 15)

See ?grid for details of how to specify the grid as per your abline() version.