All you need to try out in this recipe is to run R and type the recipe in the command prompt. You can also choose to save the recipe as a script so that you can use it again later on.

To set the plot background color to gray, we use the bg argument in the par() command:

par(bg="gray")
plot(rnorm(100))

The bg argument of the par() command sets the background color for the entire plotting area, including the margins for any subsequent plots on the same device. Until the plotting device is closed or a new device is initiated, the background color stays the same.

It is more likely that we want to set the background color only for the plot region (within the axes) but there is no straightforward way to do this in R. We must draw a rectangle of the desired color in the background and then create our graph on top of it:

plot(rnorm(1000),type="n")
x<-par("usr")
rect(x[1],x[3],x[2],x[4],col="lightgray ")
points(rnorm(1000))

First, we draw the plot with the type parameter set to n so that the plotted elements are invisible. This does not show the graph points or lines but sets the axes up, which we need for the next step.

The par("usr") part gets us the coordinates of the plot region in a vector of form c(xleft, xright, ybottom, ytop). We then use the rect() function to draw a rectangle with a fill color that we wish to use for the plot background. Note that rect() takes a set of arguments that represent the xleft, ybottom, xright, and ytop coordinates. So, we must pass the values we obtained from par("usr") in the correct order. Then, finally, we redraw the graph with the correct type (points or lines). The redrawn graph looks like the following figure: