Reorder an x or y axis within facets

Reorder a column before plotting with faceting, such that the values are ordered within each facet. This requires two functions: reorder_within applied to the column, then either scale_x_reordered or scale_y_reordered added to the plot. This is implemented as a bit of a hack: it appends ___ and then the facet at the end of each string.

reorder_within(x, by, within, fun = mean, sep = "___", desc = FALSE, ...)

scale_x_reordered(..., sep = "___")

scale_y_reordered(..., sep = "___")

Source

Function was forked from personal R package of David Robinson, "drlib": https://github.com/dgrtwo/drlib

Arguments

x

Vector to reorder.

by

Vector of the same length, to use for reordering.

within

Vector of the same length that will later be used for faceting

fun

Function to perform within each subset to determine the resulting ordering. By default, mean.

sep

Separator to distinguish the two. You may want to set this manually if ___ can exist within one of your labels.

desc

Set to TRUE if you wish to have the columns in descending order.

...

In reorder_within arguments passed on to reorder. In the scale functions, extra arguments passed on to scale_x_discrete or scale_y_discrete.

Examples

library(tidyr)
library(ggplot2)

iris_gathered <- gather(iris, metric, value, -Species)

# reordering doesn't work within each facet (see Sepal.Width):
ggplot(iris_gathered, aes(reorder(Species, value), value)) +
  geom_boxplot() +
  facet_wrap(~ metric)


# reorder_within and scale_x_reordered work.
# (Note that you need to set scales = "free_x" in the facet)
ggplot(iris_gathered, aes(reorder_within(Species, value, metric), value)) +
  geom_boxplot() +
  scale_x_reordered() +
  facet_wrap(~ metric, scales = "free_x")