viridis (version 0.2.5)

viridis: Matplotlib 'viridis' color map

Description

This function creates a vector of n equally spaced colors along the Matplolib 'viridis' color map created by https://github.com/stefanv{Stéfan van der Walt} and https://github.com/njsmith{Nathaniel Smith}. This color map is designed in such a way that it will analytically be perfectly perceptually-uniform, both in regular form and also when converted to black-and-white. It is also designed to be perceived by readers with the most common form of color blindness.

Usage

viridis(n, alpha = 1)
viridisMap(n = 256, alpha = 1)

Arguments

n

The number of colors ($\ge 1$) to be in the palette.

alpha

The alpha transparency, a number in [0,1], see argument alpha in hsv.

Value

• viridis returns a character vector, cv, of color hex codes. This can be used either to create a user-defined color palette for subsequent graphics by palette(cv), a col = specification in graphics functions or in par.

  viridisMap returns a n lines data frame containing the red (R), green (G), blue (B) and alpha (alpha) channels of n equally spaced colors along the 'viridis' color map. n = 256 by default, which corresponds to the data from the original 'viridis' color map in Matplotlib.

Details

Semi-transparent colors ($0 < alpha < 1$) are supported only on some devices: see rgb.

Examples

library(ggplot2)
library(hexbin)

dat <- data.frame(x = rnorm(10000), y = rnorm(10000))

ggplot(dat, aes(x = x, y = y)) +
  geom_hex() + coord_fixed() +
  scale_fill_gradientn(colours = viridis(256))

# using code from RColorBrewer to demo the palette
n = 200
image(
  1:n,1,as.matrix(1:n)
  ,col=viridis(n)
  ,xlab="viridis n",ylab="",xaxt="n",yaxt="n",bty="n"
)