# Racetrack Plot

Original source: http://stackoverflow.com/questions/15751442/making-a-circular-barplot-with-a-hollow-center-aka-race-track-plot

Want to learn more? I recommend working through: R for Data Science, R Cookbook, and R Graphics Cookbook.

```# load the ggplot2 library
library(ggplot2)
```
```# create some simulated data
Category <- c("Electronics", "Appliances", "Books", "Music", "Clothing",
"Cars", "Food/Beverages", "Personal Hygiene",
"Personal Health/OTC", "Hair Care")
Percent <- c(81, 77, 70, 69, 69, 68, 62, 62, 61, 60)
internetImportance <- data.frame(Category,Percent)
```

## Create a dataframe that contains the legend information

```# create a variable called len that equals 4
len <- 4
```
```# create a data frame with three elements, Category, Percent, and Category2. this is all blank data so that the middle of the racetrack is blank
df2 <- data.frame(Category = letters[1:len], Percent = rep(0, len),
Category2 = rep("", len))
```
```# create a new Category2 variable in the internetImportance df that contains the category name, a dash, the importance percent, and a percent sign
internetImportance\$Category2 <-
paste0(internetImportance\$Category," - ",internetImportance\$Percent,"%")
```
```# append number to category name
internetImportance <- rbind(internetImportance, df2)
```
```# set factor so it will plot in descending order
internetImportance\$Category <-
factor(internetImportance\$Category,
levels=rev(internetImportance\$Category))
```

## Plot

```# great the ggplot data
ggplot(internetImportance, aes(x = Category, y = Percent,
fill = Category2)) +
# create a bar plot
geom_bar(width = 0.9, stat="identity") +
scale_fill_brewer(palette="Set3") +
# curve the bar chart
coord_polar(theta = "y") +
# remove the x and y axis labels
xlab("") + ylab("") +
# let the "circumference" of the racetrack to 100
ylim(c(0,100)) +
# add a title at the top of the chart
ggtitle("Top Product Categories Influenced by Internet") +
geom_text(data = internetImportance, hjust = 1, size = 3,
aes(x = Category, y = 0, label = Category2)) +
# add the text in the middle of the racetrack
geom_text(label="GLOBAL", x=.5, y=.5, size=4) +
# use the minimal theme to make is pretty
theme_minimal() +
# remove the external legend, and remove all the extra elements
theme(legend.position = "none",
panel.grid.major = element_blank(),
panel.grid.minor = element_blank(),
axis.line = element_blank(),
axis.text.y = element_blank(),
axis.text.x = element_blank(),
axis.ticks = element_blank())
```