Diverging colour gradient

Usage

scale_colour_gradient2(..., low = muted("red"), mid = "white", high = muted("blue"),
  midpoint = 0, space = "rgb", na.value = "grey50", guide = "colourbar")

scale_fill_gradient2(..., low = muted("red"), mid = "white", high = muted("blue"),
      midpoint = 0, space = "rgb", na.value = "grey50", guide = "colourbar")

scale_color_gradient2(..., low = muted("red"), mid = "white", high = muted("blue"),
      midpoint = 0, space = "rgb", na.value = "grey50", guide = "colourbar")

Arguments

midpoint
The midpoint (in data value) of the diverging scale. Defaults to 0.
guide
Type of legend. Use "colourbar" for continuous colour bar, or "legend" for discrete colour legend.
...
Other arguments passed on to discrete_scale to control name, limits, breaks, labels and so forth.
na.value
Colour to use for missing values
low
colour for low end of gradient.
mid
colour for mid point
high
colour for high end of gradient.
space
colour space in which to calculate gradient. "Lab" usually best unless gradient goes through white.

Description

Diverging colour gradient

Examples

dsub <- subset(diamonds, x > 5 & x < 6 & y > 5 & y < 6) dsub$diff <- with(dsub, sqrt(abs(x-y))* sign(x-y)) (d <- qplot(x, y, data=dsub, colour=diff))

# Change scale name d + scale_colour_gradient2(expression(sqrt(abs(x - y))))

d + scale_colour_gradient2("Difference\nbetween\nwidth and\nheight")

# Change limits and colours d + scale_colour_gradient2(limits=c(-0.2, 0.2))

# Using "muted" colours makes for pleasant graphics # (and they have better perceptual properties too) library(scales) # for muted d + scale_colour_gradient2(low="red", high="blue")

d + scale_colour_gradient2(low=muted("red"), high=muted("blue"))

# Using the Lab colour space also improves perceptual properties # at the price of slightly slower operation d + scale_colour_gradient2(space="Lab")

# About 5% of males are red-green colour blind, so it's a good # idea to avoid that combination d + scale_colour_gradient2(high=muted("green"))

# We can also make the middle stand out d + scale_colour_gradient2(mid=muted("green"), high="white", low="white")

# or use a non zero mid point (d <- qplot(carat, price, data=diamonds, colour=price/carat))

d + scale_colour_gradient2(midpoint=mean(diamonds$price / diamonds$carat))

# Fill gradients work much the same way p <- qplot(letters[1:5], 1:5, fill= c(-3, 3, 5, 2, -2), geom="bar") p + scale_fill_gradient2("fill")

# Note how positive and negative values of the same magnitude # have similar intensity