We will continue using the base graphics library functions, so we need not load any additional library or package. We just need to run the recipe code at the R prompt. We can also save the code as a script to use it later. Here, we will use the metals.csv example dataset again:

metals<-read.csv("metals.csv")

We can build a box plot with custom colors, widths, and styles in the following way:

boxplot(metals[,-1],
border = "white",col = "black",boxwex = 0.3,
medlwd=1, whiskcol="black",staplecol="black",
outcol="red",cex=0.3,outpch=19,
main="Summary of metal concentrations by Site")

grid(nx=NA,ny=NULL,col="gray",lty="dashed")

We have used a few different arguments in the example to change the styling of the box plot. The first two are col and border, which set the box color and border color respectively. Note that the border argument also sets the color for the median line, unless it is specified using the medcol argument.

In the example, in addition to using boxwex for adjusting box widths, we used medlwd to set the width of the median line. We set the color of the whiskers and staple using whiskcol and staplecol respectively. The color and symbol type of the outlier points were set using outcol and outpch respectively. The size of the points was set using the cex argument.

We can set the color, size, and styling for each of the components. If you type ?bxp at the R prompt, you can see the help section for the bxp() function which is called by boxplot() to do the actual drawing. The following is a summary: