reposition_legend: Reposition a legend onto a panel

In lemon: Freshing Up your 'ggplot2' Plots

Reposition a legend onto a panel

Description

Repositions a legend onto a panel, by either taking it from the same ggplot, or by using another. Works on both ggplot2 and gtable objects, and can accept any grob as legend.

Usage

reposition_legend(
  aplot,
  position = NULL,
  legend = NULL,
  panel = "panel",
  x = NULL,
  y = NULL,
  just = NULL,
  name = "guide-box",
  clip = "on",
  offset = c(0, 0),
  z = Inf,
  plot = TRUE
)

Arguments

aplot	a ggplot2 or gtable object.
position	Where to place the legend in the panel. Overrules just argument.
legend	The legend to place, if NULL (default), it is extracted from aplot if this is a ggplot2 object.
panel	Name of panel in gtable. See description.
x	horisontal coordinate of legend, with 0 at left.
y	vertical coordiante of legend, with 0 at bottom.
just	'Anchor point' of legend; it is this point of the legend that is placed at the x and y coordinates.
name, clip, z	Parameters forwarded to gtable_add_grob.
offset	Numeric vector, sets distance from edge of panel. First element for horisontal distance, second for vertical. Not used by arguments x and y.
plot	Logical, when TRUE (default), draws plot with legend repositioned on a new page.

Details

To modify the look of the legend, use themes and the natural ggplot functions found in guide_legend.

Positioning is done by argument position which places the panel relative in panel (see below). position resolves to three variables, x, y, and just. x and y is the coordinate in panel, where the anchorpoint of the legend (set via just) is placed. In other words, just='bottom right' places the bottom right corner of the legend at coordinates (x,y).

The positioning can be set by argument position alone, which can be further nudged by setting position, x, and y. Alternatively, manually positioning can be obtained by setting arguments. x, y, and just.

Panel name is by default panel, but when using facets it typically takes the form panel-{col}-{row}, but not for wrapped facets. Either print result from ggplotGrob or use gtable_show_names to display all the names of the gtable object.

panel takes multiple names, and will then use these components' extremes for placing the legend.

If panel is an integer vector of length 2 or 4, these elements are used directly for top-left and bottom-right coordinates.

Value

gtable object, invisibly, with legend repositioned. Can be drawn with grid.draw.

Author(s)

Stefan McKinnon Edwards <[e-mail]>

See Also

g_legend, grid_arrange_shared_legend and gtable_show_names for displaying names of facet's panels.

Examples

library(ggplot2)
dsamp <- diamonds[sample(nrow(diamonds), 1000), ]
(d <- ggplot(dsamp, aes(carat, price)) +
 geom_point(aes(colour = clarity)))

reposition_legend(d + theme(legend.position='bottom'), 'bottom right')

# To change the orientation of the legend, use theme's descriptors.
reposition_legend(d + theme(legend.position='bottom'), 'top left')

# Use odd specifications, here offset the legend with half its height from the bottom.
reposition_legend(d + theme(legend.position='bottom'), x=0.3, y=0, just=c(0, -0.5))

# For using with facets:
reposition_legend(d + facet_grid(.~cut), 'top left', panel = 'panel-1-5')

lemon documentation built on May 29, 2024, 8:48 a.m.