gglegend(fn)

# Small function to display plots only if it's interactive
p_ <- GGally::print_if_interactive

# display regular plot
p_(ggally_points(iris, ggplot2::aes(Sepal.Length, Sepal.Width, color = Species)))

# Make a function that will only print the legend
points_legend <- gglegend(ggally_points)
p_(points_legend(iris, ggplot2::aes(Sepal.Length, Sepal.Width, color = Species)))

# produce the sample legend plot, but supply a string that 'wrap' understands
same_points_legend <- gglegend("points")
identical(
  attr(attr(points_legend, "fn"), "original_fn"),
  attr(attr(same_points_legend, "fn"), "original_fn")
)

# Complicated examples
custom_legend <- wrap(gglegend("points"), size = 6)
p_(custom_legend(iris, ggplot2::aes(Sepal.Length, Sepal.Width, color = Species)))

# Use within ggpairs
pm <- ggpairs(
  iris, 1:2,
  mapping = ggplot2::aes(color = Species),
  upper = list(continuous = gglegend("points"))
)
p_(pm)

# Place a legend in a specific location
pm <- ggpairs(iris, 1:2, mapping = ggplot2::aes(color = Species))
# Make the legend
pm[1,2] <- points_legend(iris, ggplot2::aes(Sepal.Width, Sepal.Length, color = Species))
p_(pm)