Use circular colorscale in R

circular-color.R

library(ggplot2)

df <- data.frame(x = rnorm(100), y = rnorm(100))

df$dir <- with(df, atan2(y, x))
df$t <- 1:nrow(df)

## The default is, of course, ridiculous. 
(g <- ggplot(df, aes(dir, t)) + 
    geom_point(aes(color = dir)) +
    coord_polar())

## First approach. It doesn't work.
g + scale_color_gradient2(low = "blue", high = "blue", mid = "red")

library(colorspace)

angle <- seq(0, 2*pi, length.out = 20)
A <- 100*sin(angle)
B <- 100*cos(angle)

## Two different ways. Which is better?
plot(circular2 <- polarLAB(70, 60, angle*180/pi))
plot(circular <- LAB(60, A, B))


g + scale_color_gradientn(colours = hex(circular, fixup = TRUE))
g + scale_color_gradientn(colours = hex(circular2, fixup = TRUE))

library(ggplot2)

df <- data.frame(x = rnorm(100), y = rnorm(100))

df$dir <- with(df, atan2(y, x))
df$t <- 1:nrow(df)

## The default is, of course, ridiculous. 
(g <- ggplot(df, aes(dir, t)) + 
        geom_point(aes(color = dir)) +
        coord_polar())

## First approach. It doesn't work.
g + scale_color_gradient2(low = "blue", high = "blue", mid = "red")

library(colorspace)

angle <- seq(0, 2*pi, length.out = 20)
A <- 100*sin(angle)
B <- 100*cos(angle)

## Two different ways. Which is better?
plot(circular2 <- polarLAB(70, 60, angle*180/pi))

plot(circular <- LAB(60, A, B))

g + scale_color_gradientn(colours = hex(circular, fixup = TRUE))

g + scale_color_gradientn(colours = hex(circular2, fixup = TRUE))