# PieCharts -- Create pie charts of car sales
# for autosales.txt dataset.

# Read data frame from file.
autos <- read.table("autosales.txt", header=T, sep="\t")
cars <- autos$cars
days <- autos$days

# Send graphs to disk file.
pdf("pie-charts.pdf")

# Create simple pie chart.
pie(cars)

# Add day of week labels and title.
pie(cars, labels=days, col=rainbow(length(cars)),
   main="Car Sales by Day of Week")

# Change colors, label using percentages, and add a legend.
colors <- c("white", "gray70", "gray90", "gray50", "black")
car_labels <- round((cars / sum(cars)) * 100, 1)
car_labels <- paste(days, ": ", car_labels, "%", sep="")
pie(cars, main="Car Sales by Day of Week", col=colors,
   labels=car_labels)

# Reset graphics output to default.
dev.off( )