Aligning facetted plots and legends

Question

I'm trying to plot facets with each facet having its own legend. However, I am having some trouble to get it all aligned properly.

dat <- structure(list(group1 = structure(c(1L, 1L, 2L, 2L, 2L), .Label = c("A", 
"B"), class = "factor"), group2 = structure(c(1L, 2L, 1L, 3L, 
2L), .Label = c("a", "b", "c"), class = "factor"), x = c("1", 
"2", "3", "4", "2"), y = c("1", "2", "3", "4", "3")), .Names = c("group1", 
"group2", "x", "y"), row.names = c(NA, 5L), class = "data.frame")

dat <- split(dat, f = dat$group1)

library(ggplot2)
p1 <- ggplot(dat$A) +
  geom_point(aes(x=x, y=y, colour=group2)) +
  facet_wrap(~group1) +
  guides(colour=guide_legend(nrow=2)) +
  scale_colour_manual(values=c(a = "green", b = "red", c = "blue"), 
                      labels=c(a = "green", b = "red", c = "blue"))

p2 <- p1 %+% dat$B

Using gridExtra the problem is that the plots don't align:

library(gridExtra)
grid.arrange(p1, p2, p2, p1, ncol=2)

And using cowplot the legends are somewhat centred:

library(cowplot)
plot_grid(p1, p2, p2, p1, ncol=2, align="hv")

I tried adding legend.justification and/or legend.position but with no effect.

How can I get both the plots/legends aligned?

Answer 1

You could try the experimental egg package.

grid.draw(ggarrange(plots=list(p1,p2,p2,p1)))

Note that ggplot2 has a habit of breaking this type of code with every update, so consider it a fragile workaround.