Add a horizontal or vertical line to the current plot

Usage

add_line(at = NULL, outer = FALSE, horizontal = TRUE, ...)

Source

The source code of this function was taken from this stackoverflow question.

Arguments

at: Numeric; the relative location of where the line should be plotted. Cannot be NULL.
outer: Logical; if TRUE, the line is plotted outside of the plotting area. Default is FALSE.
horizontal: Logical; if TRUE (default), a horizontal line is added. If FALSE, a vertical line is added.
...: Additional graphical parameters passed to graphics::abline.

Value

Invisible; the function is called for its side effect of drawing on the current plot.

Examples

# Horizontal line
par(oma = c(1, 1, 1, 1), mar = c(3, 3, 1, 1))
plot(seq_len(100))

# add horizontal line
add_line(at = 0.25)
# add horizontal line that extends outside the plot area
add_line(at = 0.5, outer = TRUE)
# the same line but with a different line width and colour
add_line(at = 0.75, outer = TRUE, lwd = 3, col = "red")


# ---------------------------------------------

plot(seq_len(100))
# add vertical line
add_line(horizontal = FALSE, at = 0.25)
# add vertical line that extends outside the plot area
add_line(horizontal = FALSE, at = 0.5, outer = TRUE)
# the same line but with a different line width and colour
add_line(horizontal = FALSE, at = 0.75, outer = TRUE, lwd = 3, col = "red")