Polar Circles

November 16, 2015
By

(This article was first published on Ripples, and kindly contributed to R-bloggers)

You cannot find peace by avoiding life (Virginia Woolf)

Combining polar coordinates, RColorBrewer palettes, ggplot2 and a simple trigonometric function to define the width of the tiles is easy to produce nice circular plots like these:

polar_flower4polar_flower2polar_flower1polar_flower3

Do you want to try? Here you have the code:

library(ggplot2)
library(dplyr)
library(RColorBrewer)
n=500
m=50
w=sapply(seq(from=-3.5*pi, to=3.5*pi, length.out=n), function(x) {abs(sin(x))})
x=c(1)
for (i in 2:n) {x[i]=x[i-1]+1/2*(w[i-1]+w[i])}
expand.grid(x=x, y=1:m) %>%
  mutate(w=rep(w, m))-> df
opt=theme(legend.position="none",
          panel.background = element_rect(fill="white"),
          panel.grid=element_blank(),
          axis.ticks=element_blank(),
          axis.title=element_blank(),
          axis.text=element_blank())
ggplot(df, aes(x=x,y=y))+geom_tile(aes(fill=x, width=w))+ 
  scale_fill_gradient(low=brewer.pal(9, "Greens")[1], high=brewer.pal(9, "Greens")[9])+
  coord_polar(start = runif(1, min = 0, max = 2*pi))+opt
ggplot(df, aes(x=x,y=y))+geom_tile(aes(fill=w, width=w))+ 
  scale_fill_gradient(low=brewer.pal(9, "Reds")[1], high=brewer.pal(9, "Reds")[9])+ 
  coord_polar(start = runif(1, min = 0, max = 2*pi))+opt
ggplot(df, aes(x=x,y=y))+geom_tile(aes(fill=y, width=w))+ 
  scale_fill_gradient(low=brewer.pal(9, "Purples")[1], high=brewer.pal(9, "Purples")[9])+ 
  coord_polar(start = runif(1, min = 0, max = 2*pi))+opt
ggplot(df, aes(x=x,y=y))+geom_tile(aes(fill=w*y, width=w))+ 
  scale_fill_gradient(low=brewer.pal(9, "Blues")[9], high=brewer.pal(9, "Blues")[1])+ 
  coord_polar(start = runif(1, min = 0, max = 2*pi))+opt

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