Closing the lines in a ggplot2 radar / spider chart

Question

I need a flexible way to make radar / spider charts in ggplot2. From solutions I\'ve found on github and the ggplot2 group, I\'ve come this far:

library(ggpl         


        

Answer 1

It turns out than geom_polygom still produces a polygon in the polar coordinates so that

# rescale all variables to lie between 0 and 1
scaled <- as.data.frame(lapply(mtcars, ggplot2:::rescale01))
scaled$model <- rownames(mtcars)    # add model names as a variable
# melt the dataframe
mtcarsm <- reshape2::melt(scaled)
# plot it as using the polygon geometry in the polar coordinates
ggplot(mtcarsm, aes(x = variable, y = value)) +
geom_polygon(aes(group = model), color = "black", fill = NA, size = 1) +
coord_polar() + facet_wrap( ~ model) +
theme(strip.text.x = element_text(size = rel(0.8)),
    axis.text.x = element_text(size = rel(0.8)),
    axis.ticks.y = element_blank(),
    axis.text.y = element_blank()) +
xlab("") + ylab("")

works perfectly...