While pie charts are well known, they are not typically as useful as other charts in a data analysis. A pie chart is shown in Figure LABEL:emailNumberPieChart alongside a bar plot. It is generally more difficult to compare group sizes in a pie chart than in a bar plot, especially when categories have nearly identical counts or proportions. In the case of the none and big categories, the difference is so slight you may be unable to distinguish any difference in group sizes for either plot!
R> pie(table(email[,21]),radius=0.75)
R> barplot(table(email[,21]))