Using R for Introductory Statistics : John Verzani

Appendix D 364D.2 Creating new graphics in RIn this section we illustrate some of the aforementioned techniques by creating graphicsfor a squareplot and a scatterplot with additional information in the margins.■ Example D.3: A squareplot alternative to barplots and pie chartsThe New York Times does an excellent job with its statistical graphics. Its staff is bothcareful to use graphics in an appropriate manner and creative in making new graphics toshowcase details. A case in point is a graphic the Times uses in place of a barplot, dotplotor pie chart that we will call a squareplot.Figure D.2 Squareplot of c (21, 7, 6)The squareplot shows counts of categorical data. Unlike the barplot, the squareplot makesit easy to see the exact counts. Unlike the dotplot, it is can be read without consulting thescales. Unlike the pie chart, the squareplot’s relative areas are easy to discern.The basic idea is to use squares of different colors to represent each count. Thesquares and colors are laid out in a way that facilitates counting values and comparingdifferent plots. Figure D.2 shows an example, from which we can count that thecategories have counts 21, 7, and 6.The UsingR package contains the function squareplot (), which is reproduced below.Creating the graphic is pretty simple. A helper function to draw a square using polygon ()is defined. Then the larger square is defined and laid out. An empty plot is made. Then anew vector, cols, is created to match the colors with the counts. This is done with rep () torepeat the colors. Finally, the squares are made and colored one-by-one using a for loop.The functions floor for the integer portion of a number and %% for the remainder afterdivision are employed.squareplot