Remove spacing around plotting area in r

Question

When I create the following plot I get unwanted space between the plotting area and the axis (i.e. the white space between the blue box and the x axis. How can I remove this

Answer 1

There is an argument in function plot that handles that: xaxs (and yaxs for the y-axis). As default it is set to xaxs="r" meaning that 4% of the axis value is left on each side. To set this to 0: xaxs="i". See the xaxs section in ?par for more information.

plot(c(1,2.75),c(1,2.75),type="n",main="title",xlab="site.x",ylab="ylab", xaxs="i", yaxs="i")
rect(xleft,ybottom,xright,ytop,col=c("blue","red","green"))