Don't reorder data during faceting.

[clauswilke]

This addresses the underlying reason for #2693, data are reordered during faceting. With this patch, data order is not changed anymore in facet_grid() or facet_wrap(). This enables data vectors to be provided via aes() or as parameters.

library(ggplot2)

df <- data.frame(x = 1:4,
                 y = 1:4,
                 label1 = c("a", "b", "a", "b"),
                 label2 = c("c", "c", "d", "d"),
                 colour =  c("magenta", "green", "red", "cyan"))

ggplot(df, aes(x, y, colour = df$colour)) +
  geom_point(size = 3) +
  facet_wrap(~label1) +
  scale_colour_identity()

ggplot(df, aes(x, y, colour = df$colour)) +
  geom_point(size = 3) +
  facet_grid(label1~label2) +
  scale_colour_identity()

# things still work if some data points are removed by scale limits
ggplot(df, aes(x, y, colour = df$colour)) +
  geom_point(size = 3) +
  facet_wrap(~label1) +
  scale_x_continuous(limits = c(1.5, 3.5)) +
  scale_colour_identity()
#> Warning: Removed 2 rows containing missing values (geom_point).

ggplot(df, aes(x, y, colour = df$colour)) +
  geom_point(size = 3) +
  facet_grid(label1~label2) +
  scale_x_continuous(limits = c(1.5, 3.5)) +
  scale_colour_identity()
#> Warning: Removed 2 rows containing missing values (geom_point).

Created on 2018-06-10 by the reprex package (v0.2.0).

[hadley]

Let's hold of merging this until after the release.

[hadley]

Can you please add a news bullet?

Thanks for diagnosing this — it's going to fix a lot of broken plots in the wild!

[clauswilke]

News bullet added.

[hadley]

Can you remove this heading please? It's easier to add these just before release. (http://style.tidyverse.org/news.html#news-bullets)

[clauswilke]

Good you flagged that. I had also messed up the main heading in the rebase. Should be good now.

[lock]

This old issue has been automatically locked. If you believe you have found a related problem, please file a new issue (with reprex) and link to this issue. https://reprex.tidyverse.org/