Add a Grid to a Plot

This function adds a grid to an existing plot (like box()). User can specify coordinates on x- and/or y-axis where to draw vertical and/or horizontal lines respectively. User can also color the background of the plot area and add a box around this area (if required).

addGrid(
  at_x,
  at_y,
  col = NA,
  border = "black",
  lwd = 1,
  lty = 1,
  box = FALSE,
  ...
)

Arguments

at_x	coordinates on the x-Axis where to draw vertical lines.
at_y	coordinates on the y-Axis where to draw horizontal lines.
col	the color of the background.
border	the color of lines (and box).
lwd	the width of lines (see par()).
lty	the type of lines (see par()).
box	a boolean. If TRUE add a box around the plot area.
...	other graphical parameters as in par().

Details

If user does not specify at_x and at_y, the grid is aligned with the tick marks on the corresponding default axes (computed by axTicks).

Author

Nicolas CASAJUS, nicolas.casajus@gmail.com

Examples

maps::map()
addGrid()
addGrid(box = TRUE)
addGrid(col = "#ff000044", border = "green", box = TRUE)

maps::map()
addGrid(at_x = axTicks(1), border = "blue", lwd = 2)
addGrid(at_y = axTicks(2), border = "red")
addGrid(at_x = NULL, at_y = NULL, lwd = 3, box = TRUE)