Grid in an R plot

Question

Is there a command to easily add a grid onto an R plot?

Answer 1

If you are not using a custom tick interval, you can control the grid and axes parameters directly from the plot() command:

plot(cumsum(rnorm(100)), type='l', panel.first=grid())

The plot.default() documentation provides more information about these parameters.

Answer 2

The grid command seems to draw grid lines where-ever it feels like. I usually use abline to put lines exactly where I want them. For example,

abline(v=(seq(0,100,25)), col="lightgray", lty="dotted")
abline(h=(seq(0,100,25)), col="lightgray", lty="dotted")

Good luck!

Answer 3

I agree with cbare. Use abline to draw lines only where you really need.

Example from my last code:

abline(v=c(39448, 39814), col="grey40")
abline(h=c(-0.6, -0.4, -0.2, 0.2,0.4,0.6), col="grey10", lty="dotted") 

remember that:

v is for vertical lines. h for horizontal.

exploit the commands

lty for dotted line color for light coloured line

in order to obtain "no heavy grid".

Answer 4

See help(grid) which works with standard graphics -- short example:

R> set.seed(42)
R> plot(cumsum(rnorm(100)), type='l')
R> grid()

The ggplot2 package defaults to showing grids due to its 'Grammar of Graphics' philosophy. And lattice has a function panel.grid() you can use in custom panel functions.

By the way, there are search functions for help as e.g. help.search("something") and there is an entire package called sos to make R web searches more fruitful.