guide_bins: A binned version of guide_legend

Description

This guide is a version of the guide_legend() guide for binned scales. It differs in that it places ticks correctly between the keys, and sports a small axis to better show the binning. Like guide_legend() it can be used for all non-position aesthetics though colour and fill defaults to guide_coloursteps(), and it will merge aesthetics together into the same guide if they are mapped in the same way.

Usage

guide_bins(
  title = waiver(),
  title.position = NULL,
  title.theme = NULL,
  title.hjust = NULL,
  title.vjust = NULL,
  label = TRUE,
  label.position = NULL,
  label.theme = NULL,
  label.hjust = NULL,
  label.vjust = NULL,
  keywidth = NULL,
  keyheight = NULL,
  axis = TRUE,
  axis.colour = "black",
  axis.linewidth = 0.5,
  axis.arrow = NULL,
  direction = NULL,
  default.unit = "line",
  override.aes = list(),
  reverse = FALSE,
  order = 0,
  show.limits = NULL,
  ...
)

Value

A guide object

Arguments

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.
label.vjust: A numeric specifying vertical justification of the label text.
keywidth: A numeric or a grid::unit() object specifying the width of the legend key. Default value is legend.key.width or legend.key.size in theme().
keyheight: A numeric or a grid::unit() object specifying the height of the legend key. Default value is legend.key.height or legend.key.size in theme().
axis: Logical. Should a small axis be drawn along the guide
axis.colour, axis.linewidth: Graphic specifications for the look of the axis.
axis.arrow: A call to arrow() to specify arrows at the end of the axis line, thus showing an open interval.
direction: A character string indicating the direction of the guide. One of "horizontal" or "vertical."
default.unit: A character string indicating grid::unit() for keywidth and keyheight.
override.aes: A list specifying aesthetic parameters of legend key. See details and examples.
reverse: logical. If TRUE the order of legends is reversed.
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.
show.limits: Logical. Should the limits of the scale be shown with labels and ticks.
...: ignored.

Use with discrete scale

This guide is intended to show binned data and work together with ggplot2's binning scales. However, it is sometimes desirable to perform the binning in a separate step, either as part of a stat (e.g. stat_contour_filled()) or prior to the visualisation. If you want to use this guide for discrete data the levels must follow the naming scheme implemented by base::cut(). This means that a bin must be encoded as "(<lower>, <upper>]" with <lower> giving the lower bound of the bin and <upper> giving the upper bound ("[<lower>, <upper>)" is also accepted). If you use base::cut() to perform the binning everything should work as expected, if not, some recoding may be needed.

Examples

Run this code

p <- ggplot(mtcars) +
  geom_point(aes(disp, mpg, size = hp)) +
  scale_size_binned()

# Standard look
p

# Remove the axis or style it
p + guides(size = guide_bins(axis = FALSE))

p + guides(size = guide_bins(show.limits = TRUE))

p + guides(size = guide_bins(
  axis.arrow = arrow(length = unit(1.5, 'mm'), ends = 'both')
))

# Guides are merged together if possible
ggplot(mtcars) +
  geom_point(aes(disp, mpg, size = hp, colour = hp)) +
  scale_size_binned() +
  scale_colour_binned(guide = "bins")