Reversing y-axis in an individual ggplot facet

Question

I am plotting a range of different data measured on the same individuals next to each other in facets. For some types of data a positive value is "good" and for some a negative value is "good". The latter types of variables are usually plotted with flipped y-axes. Is it possible to modify axis directions in individual facets with ggplot?

dat <- data.frame(type = rep(c('A', 'B'), each = 10), x = 1:10, y = rnorm(20))

ggplot(dat, aes(x, y)) + geom_point() + facet_wrap( ~ type, scales = 'free_y')

For example, could I do the above plot with the y-axis for B reversed?

score 3 · Accepted Answer · answered May 11 '17 at 12:45

I'm not sure if that's possible, so I would opt for a solution using the grid.arrange function from the gridExtra package.

library(gridExtra)
library(ggplot2)

dat <- data.frame(type = rep(c('A', 'B'), each = 10), x = 1:10, y = rnorm(20),
                  stringsAsFactors = FALSE)

p_A <- ggplot(subset(dat, type == 'A'), aes(x, y)) + geom_point() + facet_wrap( ~ type, scales = 'free_y')+
    scale_y_continuous(breaks = c(-1,0,1))
p_B <- ggplot(subset(dat, type == 'B'), aes(x, y)) + geom_point() + facet_wrap( ~ type, scales = 'free_y')+
    scale_y_reverse(breaks = c(-1,0,1))

grid.arrange(p_A, p_B, nrow = 1)

Thank you for the answer. I had a feeling that this was the only real solution that didn't require massive amounts of coding. I'll accept it as it is probably the best solution available, but I had really hoped for something that generalized well to more complex faceting with `facet_grid`. — Lars Lau Raket, May 15 '17 at 07:37

score 3 · Answer 2 · edited Feb 11 '21 at 16:45

This can now also be achieved using the ggh4x package or the facetscales package (see here for facetscales approach):

library(ggh4x)

dat <- data.frame(type = rep(c('A', 'B'), each = 10), x = 1:10, y = rnorm(20))

scales <- list(
  scale_y_continuous(),
  scale_y_reverse()
  )

ggplot(dat, aes(x, y)) + 
  geom_point() +
  facet_wrap( ~ type, scales = 'free_y') +
  facetted_pos_scales(y = scales)

Reversing y-axis in an individual ggplot facet

2 Answers2

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