Continuous colour ramp guide

A colour ramp bar guide that shows continuous colour ramp scales mapped onto values as a smooth gradient. Designed for use with scale_fill_ramp_continuous() and scale_colour_ramp_continuous(). Based on guide_colourbar().

guide_rampbar(
  ...,
  to = "gray65",
  available_aes = c("fill_ramp", "colour_ramp")
)

Arguments

...

Arguments passed on to ggplot2::guide_colourbar

title

A character string or expression indicating a title of guide. If NULL, the title is not shown. By default (waiver()), the name of the scale object or the name specified in labs() is used for the title.

title.position

A character string indicating the position of a title. One of "top" (default for a vertical guide), "bottom", "left" (default for a horizontal guide), or "right."

title.theme

A theme object for rendering the title text. Usually the object of element_text() is expected. By default, the theme is specified by legend.title in theme() or theme.

title.hjust

A number specifying horizontal justification of the title text.

title.vjust

A number specifying vertical justification of the title text.

label

logical. If TRUE then the labels are drawn. If FALSE then the labels are invisible.

label.position

A character string indicating the position of a label. One of "top", "bottom" (default for horizontal guide), "left", or "right" (default for vertical guide).

label.theme

A theme object for rendering the label text. Usually the object of element_text() is expected. By default, the theme is specified by legend.text in theme().

label.hjust

A numeric specifying horizontal justification of the label text. The default for standard text is 0 (left-aligned) and 1 (right-aligned) for expressions.

label.vjust

A numeric specifying vertical justification of the label text.

barwidth

A numeric or a grid::unit() object specifying the width of the colourbar. Default value is legend.key.width or legend.key.size in theme() or theme.

barheight

A numeric or a grid::unit() object specifying the height of the colourbar. Default value is legend.key.height or legend.key.size in theme() or theme.

nbin

A numeric specifying the number of bins for drawing the colourbar. A smoother colourbar results from a larger value.

raster

A logical. If TRUE then the colourbar is rendered as a raster object. If FALSE then the colourbar is rendered as a set of rectangles. Note that not all graphics devices are capable of rendering raster image.

frame.colour

A string specifying the colour of the frame drawn around the bar. If NULL (the default), no frame is drawn.

frame.linewidth

A numeric specifying the width of the frame drawn around the bar in millimetres.

frame.linetype

A numeric specifying the linetype of the frame drawn around the bar.

ticks

A logical specifying if tick marks on the colourbar should be visible.

ticks.colour

A string specifying the colour of the tick marks.

ticks.linewidth

A numeric specifying the width of the tick marks in millimetres.

draw.ulim

A logical specifying if the upper limit tick marks should be visible.

draw.llim

A logical specifying if the lower limit tick marks should be visible.

direction

A character string indicating the direction of the guide. One of "horizontal" or "vertical."

default.unit

A character string indicating grid::unit() for barwidth and barheight.

reverse

logical. If TRUE the colourbar is reversed. By default, the highest value is on the top and the lowest value is on the bottom

order

positive integer less than 99 that specifies the order of this guide among multiple guides. This controls the order in which multiple guides are displayed, not the contents of the guide itself. If 0 (default), the order is determined by a secret algorithm.

to

The color to ramp to in the guide. Corresponds to 1 on the scale.

available_aes

A vector of character strings listing the aesthetics for which a guide_rampbar() can be drawn.

Value

A guide object.

Details

This guide creates smooth gradient color bars for use with scale_fill_ramp_continuous() and scale_colour_ramp_continuous(). The color to ramp from is determined by the from argument of the scale_* function, and the color to ramp to is determined by the to argument to guide_rampbar().

Guides can be specified in each scale_* function or in guides(). guide = "rampbar" in scale_* is syntactic sugar for guide = guide_rampbar(); e.g. scale_colour_ramp_continuous(guide = "rampbar"). For how to specify the guide for each scale in more detail, see guides().

See also

scale_fill_ramp_continuous(), scale_colour_ramp_continuous().

Author

Matthew Kay

Examples

library(dplyr)
library(ggplot2)
library(distributional)

# The default guide for ramp scales is guide_legend(), which creates a
# discrete style scale:
tibble(d = dist_uniform(0, 1)) %>%
  ggplot(aes(y = 0, xdist = d)) +
  stat_slab(aes(fill_ramp = after_stat(x)), fill = "blue") +
  scale_fill_ramp_continuous(from = "red")


# We can guide_rampbar() to instead create a continuous guide, but
# it does not know what ccolor to ramp to (defaults to "gray65"):
tibble(d = dist_uniform(0, 1)) %>%
  ggplot(aes(y = 0, xdist = d)) +
  stat_slab(aes(fill_ramp = after_stat(x)), fill = "blue") +
  scale_fill_ramp_continuous(from = "red", guide = guide_rampbar())


# We can tell the guide what color to ramp to using the `to` argument:
tibble(d = dist_uniform(0, 1)) %>%
  ggplot(aes(y = 0, xdist = d)) +
  stat_slab(aes(fill_ramp = after_stat(x)), fill = "blue") +
  scale_fill_ramp_continuous(from = "red", guide = guide_rampbar(to = "blue"))