Plot a Color Legend — colorlegend • bamlss

Function to generate a color legend, the legend may be added to an existing plot or drawn in a separate plotting window.

colorlegend(color = NULL, ncol = NULL, x = NULL, breaks = NULL, 
  pos = "center", shift = 0.02, side.legend = 1L, side.ticks = 1L,
  range = NULL, lrange = NULL, width = 0.25, height = 0.05,
  scale = TRUE, xlim = NULL, ylim = NULL, plot = NULL, full = FALSE,
  add = FALSE, col.border = "black", lty.border = 1L, lwd.border = 1L,
  ticks = TRUE, at = NULL, col.ticks = "black", lwd.ticks = 1L,
  lty.ticks = 1L, length.ticks = 0.3, labels = NULL,
  distance.labels = 0, col.labels = "black", cex.labels = 1L,
  digits = 2L, swap = FALSE, symmetric = TRUE, xpd = NULL,
  title = NULL, side.title = 2, shift.title = c(0, 0),
  cex.title = 1, ...)

Arguments

color: Character, integer. The colors for the legend, may also be a function, e.g. colors = heat.colors.
ncol: Integer, the number of different colors that should be generated if color is a function.
x: Numeric, values for which the color legend should be drawn.
breaks: Numeric, a set of breakpoints for the colors: must give one more breakpoint than ncol.
pos: Character, numeric. The position of the legend. Either a numeric vector, e.g. pos = c(0.1, 0.2) will add the legend at the 10\(\%\) point in the x-direction and at the 20\(\%\) point in the y-direction of the plotting window, may also be negative, or one of the following: "bottomleft", "topleft", "topright", "bottomright", "left", "right", "top", "bottom" and "center".
shift: Numeric, if argument pos is a character, shift determines the distance of the legend from the plotting box.
side.legend: Integer, if set to 2 the legend will be flipped by 90 degrees.
side.ticks: Integer, if set to 2, the ticks and labels will be on the opposite site of the legend.
range: Numeric, specifies a range for x values for which the legend should be drawn.
lrange: Numeric, specifies the range of legend.
width: Numeric, the width of the legend, if scale = TRUE the width is proportional to the x-limits of the plotting window.
height: Numeric, the height of the legend, if scale = TRUE the height is proportional to the y-limits of the plotting window.
scale: Logical, if set to TRUE, the width and height of the legend will be calculated proportional to the x- and y-limits of the plotting window.
xlim: Numeric, the x-limits of the plotting window the legend should be added for, numeric vector, e.g., returned from function range.
ylim: Numeric, the y-limits of the plotting window the legend should be added for, numeric vector, e.g., returned from function range.
plot: Logical, if set to TRUE, the legend will be drawn in a separate plotting window.
full: Logical, if set to TRUE, the legend will be drawn using the full window range.
add: Logical, if set to TRUE, the legend will be added to an existing plot.
col.border: The color of the surrounding border line of the legend.
lty.border: The line type of the surrounding border line of the legend.
lwd.border: The line width of the surrounding border line of the legend.
ticks: Logical, if set to TRUE, ticks will be added to the legend.
at: Numeric, specifies at which locations ticks and labels should be added.
col.ticks: The colors of the ticks.
lwd.ticks: The line width of the ticks.
lty.ticks: The line type of the ticks.
length.ticks: Numeric, the length of the ticks as percentage of the height or width of the colorlegend.
labels: Character, specifies labels that should be added to the ticks.
distance.labels: Numeric, the distance of the labels to the ticks, proportional to the length of the ticks.
col.labels: The colors of the labels.
cex.labels: Text size of the labels.
digits: Integer, the decimal places if labels are numerical.
swap: Logical, if set to TRUE colors will be represented in reverse order.
symmetric: Logical, if set to TRUE, a symmetric legend will be drawn corresponding to the +- max(abs(x)) value.
xpd: Sets the xpd parameter in function par.
title: Character, a title for the legend.
side.title: Integer, 1 or 2. Specifies where the legend is placed, either on top if side.title = 1 or at the bottom if side.title = 2.
shift.title: Numeric vector of length 2. Specifies a possible shift of the title in either x- or y-direction.
cex.title: Text size for the title.
...: Other graphical parameters to be passed to function text.

Value

A named list with the colors generated, the breaks and the function map, which may be used for mapping of x values to the colors specified in argument colors, please see the examples below.

Examples

## Play with colorlegend.
colorlegend()

colorlegend(side.legend = 2)

colorlegend(side.legend = 2, side.ticks = 2)

colorlegend(height = 2)

colorlegend(width = 1, height = 0.8, scale = FALSE, 
  pos = c(0, 0.2), length.ticks = 0.5)

colorlegend(color = heat.colors, ncol = 9)

colorlegend(color = heat.colors, ncol = 9, swap = TRUE)

colorlegend(pos = "bottomleft")

colorlegend(pos = "topleft")

colorlegend(pos = "topright")

colorlegend(pos = "bottomright")



## Take x values for the color legend.
x <- runif(100, -2, 2)
colorlegend(color = diverge_hcl, x = x)

colorlegend(color = diverge_hcl, x = x, at = c(-1.5, 0, 1.5))

colorlegend(color = diverge_hcl, x = x, at = c(-1.5, 0, 1.5),
  labels = c("low", "middle", "high"))

colorlegend(color = rainbow_hcl, x = x, at = c(-1.5, 0, 1.5),
  labels = c("low", "middle", "high"), length.ticks = 1.5)

colorlegend(color = heat_hcl, x = x, at = c(-1.5, 0, 1.5),
  labels = c("low", "middle", "high"), length.ticks = 1.5,
  lwd.border = 2, lwd.ticks = 2, cex.labels = 1.5, font = 2)

colorlegend(color = topo.colors, x = x, at = c(-1.5, 0, 1.5),
  labels = c("low", "middle", "high"), length.ticks = 1.5,
  lwd.border = 2, lwd.ticks = 2, cex.labels = 1.5, font = 2,
  col.border = "green3", col.ticks = c(2, 5, 2), 
  col.labels = c(6, 4, 3))

colorlegend(color = diverge_hsv, x = x, at = c(-1.5, 0, 1.5),
  labels = c("low", "middle", "high"), length.ticks = 1.5,
  lwd.border = 2, lwd.ticks = 2, cex.labels = 1.5, font = 2,
  col.border = "green3", col.ticks = c(2, 5, 2), 
  col.labels = c(6, 4, 3), lty.border = 2, lty.ticks = c(2, 3, 2))

colorlegend(color = diverge_hsv, x = x, at = c(-1.5, 0, 1.5),
  labels = c("low", "middle", "high"), length.ticks = 1.5,
  lwd.border = 2, lwd.ticks = 2, cex.labels = 1.5, font = 2,
  col.border = "green3", col.ticks = c(2, 5, 2), 
  col.labels = c(6, 4, 3), lty.border = 2, lty.ticks = c(2, 3, 2),
  ncol = 3)

colorlegend(color = c("red", "white", "red"), x = x, at = c(-1.5, 0, 1.5),
  labels = c("low", "middle", "high"), length.ticks = 1.5,
  lwd.border = 2, lwd.ticks = 2, cex.labels = 1.5, font = 2,
  col.border = "green3", col.ticks = c(2, 5, 2), 
  col.labels = c(6, 4, 3), lty.border = 2, lty.ticks = c(2, 3, 2),
  ncol = 3, breaks = c(-2, -1, 1, 2))

colorlegend(color = diverge_hcl, x = x, range = c(-3, 3))

colorlegend(color = diverge_hcl, x = x, range = c(-3, 3), lrange = c(-6, 6))



## Combine plot with color legend.
n <- 100
x <- y <- seq(-3, 3, length.out = n)
z <- outer(sin(x), cos(x)) 
pal <- colorlegend(color = diverge_hcl, x = z, plot = FALSE)
op <- par(no.readonly = TRUE)
par(mar = c(4.1, 4.1, 1.1, 1.1))
layout(matrix(c(1, 2), nrow = 1), widths = c(1, 0.3))
image(x = x, y = y, z = z, col = pal$colors, breaks = pal$breaks)
par(mar = c(4.1, 0.1, 1.1, 3.1))
colorlegend(color = diverge_hcl, x = z, plot = TRUE, full = TRUE,
  side.legend = 2, side.ticks = 2)

par(op)


## Another example with different plot.
n <- 50
x <- sin(seq(-3, 3, length.out = n)) 
pal <- colorlegend(color = diverge_hcl, x = x, plot = FALSE)
op <- par(no.readonly = TRUE)
par(mar = c(7.1, 4.1, 1.1, 1.1))
barplot(x, border = "transparent", col = pal$map(x))
colorlegend(color = diverge_hcl, x = x, plot = FALSE, add = TRUE,
  xlim = c(0, 60), ylim = c(-1, 1), pos = c(0, -0.15), xpd = TRUE,
  scale = FALSE, width = 60, height = 0.15,
  at = seq(min(x), max(x), length.out = 9))

par(op)