Converts all legend colours to squares

Legend symbols for line graphs default to coloured lines, which can sometimes be hard to read. This function overrides the default and converts the colours to squares. This needs to be used in conjunction with some invisible point geoms so the function has a shape to reshape.

Usage

square_legend_symbols(size = 6)

Arguments

size

Numeric. Control the size of the replacement square. Default of 6 works well when ymin or ymax are not present.

Value

ggplot object

Examples

ggplot(
  data.frame(x = c(1, 2), y = c(5, 6), group = c("A", "A")),
  aes(x, y, colour = group)
  ) +
  geom_line() +
  geom_point(alpha = 0) + # The required "invisible points"
  square_legend_symbols()