ggguides (version 1.1.4)

shared_legend: Combine Plots with a Shared Legend

Description

Combines multiple ggplot objects into a grid layout with a single shared legend. Works with base ggplot and cowplot workflows (no patchwork required).

Usage

shared_legend(
  ...,
  ncol = NULL,
  nrow = NULL,
  position = c("right", "left", "bottom", "top"),
  legend_from = 1,
  rel_legend_size = 0.2
)

Value

A gtable that can be drawn with grid::grid.draw() or used with cowplot::ggdraw().

Arguments

...

ggplot objects to combine.

ncol

Number of columns in the plot grid.

nrow

Number of rows in the plot grid. If NULL (default), computed from ncol and number of plots.

position

Where to place the shared legend. One of "right" (default), "left", "bottom", or "top".

legend_from

Which plot to extract the legend from. Default is 1 (first plot). Can be an integer index or a ggplot object.

rel_legend_size

Relative size of the legend compared to the plot area. Default is 0.2 (20 percent).

Details

This function provides a simple way to create multi-panel plots with a shared legend without requiring patchwork. It:

1. Removes legends from all plots

2. Extracts the legend from the specified plot

3. Arranges plots in a grid

4. Attaches the legend to the specified position

For more complex layouts or patchwork users, see collect_legends.

See Also

get_legend, collect_legends

Examples

library(ggplot2)

p1 <- ggplot(mtcars, aes(mpg, wt, color = factor(cyl))) +
  geom_point() + labs(title = "Plot 1", color = "Cylinders")
p2 <- ggplot(mtcars, aes(mpg, hp, color = factor(cyl))) +
  geom_point() + labs(title = "Plot 2", color = "Cylinders")
p3 <- ggplot(mtcars, aes(mpg, disp, color = factor(cyl))) +
  geom_point() + labs(title = "Plot 3", color = "Cylinders")

# Side-by-side with shared legend on right
gt <- shared_legend(p1, p2, ncol = 2, position = "right")
grid::grid.newpage()
grid::grid.draw(gt)

# 2x2 grid with legend at bottom
gt <- shared_legend(p1, p2, p3, p1, ncol = 2, nrow = 2, position = "bottom")
grid::grid.newpage()
grid::grid.draw(gt)

# Stacked with legend on left
gt <- shared_legend(p1, p2, p3, ncol = 1, position = "left")
grid::grid.newpage()
grid::grid.draw(gt)