Place Legend on the Left with Proper Alignment

A one-liner to position the legend on the left side of the plot with correct left alignment for both the key box and text labels. This goes beyond simple legend.position = "left" by also setting justification and box alignment.

Usage

legend_left(by = NULL)

Arguments

by

Optional aesthetic name (character) to position only a specific legend. When specified, uses per-guide positioning via guide_legend(position = "left"). Requires ggplot2 >= 3.5.0. Common values: "colour", "fill", "size".

Value

A ggplot2 theme object (when by is NULL) or a guides specification (when by is specified).

Details

When by is NULL (default), this function sets three theme elements:

• legend.position = "left" to place the legend on the left

• legend.justification = "left" to left-justify the legend box

• legend.box.just = "left" to left-align multiple legend boxes

When by is specified, only the legend for that aesthetic is moved, allowing different legends to be placed in different positions.

See also

legend_right, legend_top, legend_bottom, legend_inside, legend_none

Examples

library(ggplot2)

# Basic usage
ggplot(mtcars, aes(mpg, wt, color = factor(cyl))) +
  geom_point() +
  legend_left()

# Works with multiple legends
ggplot(mtcars, aes(mpg, wt, color = factor(cyl), shape = factor(am))) +
  geom_point(size = 3) +
  legend_left()

# Position only the colour legend on the left
ggplot(mtcars, aes(mpg, wt, color = factor(cyl), size = hp)) +
  geom_point() +
  legend_left(by = "colour") +
  legend_bottom(by = "size")