aspect ratio of plot not working with of space = "free" in facet_grid

[dvaiman]

Hi, in ggplot I want to set the aspect ratio of the plot to a certain number.
space = "free"in facet_grid does not seem to work with theme(aspect.ratio = 1). Is there a workaround for this. Also I use coord_flip which hinders the use of coord_fixed. This is what I get:

library(ggplot2)

ggplot(mtcars, aes(hp, mpg)) +
  geom_point(aes()) +
  coord_flip()+
  theme(aspect.ratio = 1)+
  facet_grid(vars(cyl), space = "free")

[yutannihilation]

space = "free" has no effect unless the scales also vary, so probably the bellow example is more appropriate? In my understanding, there's no workaround and specifying aspect.ratio = 1 should be errored as specifying coord_fixed() does.

library(ggplot2)

p <- ggplot(mtcars, aes(hp, mpg)) +
  geom_point(aes()) +
  facet_grid(vars(cyl), scales = "free", space = "free")

# works
p

# fails properly
p + coord_fixed()
#> Error: coord_fixed doesn't support free scales

# do not fail, but the plot is strange
p + theme(aspect.ratio = 1)

^{Created on 2020-02-29 by the reprex package (v0.3.0)}

[dvaiman]

Thanks for the input, I think your example more correctly describes the problem!

[baderstine]

@thomasp85

Ah bummer. This change breaks a perfectly fine plot. :(

MWE below... If I want to make a gridded heatmap plot with geom_tile(), y is a factor, and x is character there is really no inherent scale to either axis. However, the only way to guarantee that my output plot has square tiles, while dropping irrelevant categories, is to use theme(aspect.ratio = 1) in combination with facet_grid(..., scales="free_x", and space="free_x") (unless you have other ideas?). Now this plot is impossible because it is blocked by this new error message. Can the error be changed to a warning() instead so that it is not a blocking change? There are valid use cases for this combination.

Example:

y = factor(x=c(1:6), labels=letters[1:6])
x = c("cat","dog","house","farm","road","tree")
xgrp = c("animal","animal","building","building","infrastructure","nature")
xval = rnorm(6)

dat = data.frame(y,x,xgrp, stringsAsFactors=F)

# this plot has the correct aspect ratio, but it includes every single x category in every facet, regardless of whether a value is actually present: 
ggplot(dat, aes(y = y,  x = x)) +
  geom_tile(width = .8, height = .8) +
  theme(aspect.ratio = 1) +
  facet_grid(cols = vars(xgrp, x), drop=T) # , scales="free_x", space="free_x")


# this plot drops the irrelevant x categories in each facet, however my tiles are no longer guaranteed to be square: 
ggplot(dat, aes(y = y,  x = x)) +
  geom_tile(width = .8, height = .8) +
  # theme(aspect.ratio = 1) +
  facet_grid(cols = vars(xgrp, x), drop=T, scales="free_x", space="free_x")

# this plot is perfect (in a previous version of ggplot2), but now I'm not allowed to make it:
ggplot(dat, aes(y = y,  x = x)) +
  geom_tile(width = .8, height = .8) +
  theme(aspect.ratio = 1) +
  facet_grid(cols = vars(xgrp, x), drop=T, scales="free_x", space="free_x")

[clauswilke]

@baderstine I'm surprised that this ever worked. It's unclear in the general case what exactly the output should be. You can always make individual plots and stitch them together with patchwork. Shouldn't be that much more work. See below for a rough example. You'd have to put in a little more work to remove the y axis labels from the interior plots, but that's maybe 5 additional lines of code or so.

library(tidyverse)
library(patchwork)

y <- factor(x=c(1:6), labels=letters[1:6])
x <- c("cat","dog","house","farm","road","tree")
xgrp <- c("animal","animal","building","building","infrastructure","nature")

data <- tibble(y, x, xgrp)

make_plot <- function(data) {
  ggplot(data, aes(y = y,  x = x)) +
    geom_tile(width = .8, height = .8) +
    scale_y_discrete(limits = letters[1:6]) +
    coord_fixed() +
    facet_grid(cols = vars(xgrp, x))
}

data %>%
  mutate(
    group = interaction(x, xgrp)
  ) %>%
  nest(data = -group) %>%
  mutate(
    plots = map(data, ~make_plot(.x))
  ) %>%
  pull(plots) %>%
  wrap_plots(nrow = 1)

^{Created on 2021-10-21 by the reprex package (v2.0.0)}

[baderstine]

Interesting... so something like the following does the trick (although this is digging into a separate patchwork issue thomasp85/patchwork#150)

library(tidyverse)
library(patchwork)

y <- factor(x=c(1:6), labels=letters[1:6])
x <- c("cat","dog","house","farm","road","tree")
xgrp <- c("animal","animal","building","building","infrastructure","nature")

data <- tibble(y, x, xgrp)

make_plot <- function(data) {
  p <- ggplot(data, aes(y = y,  x = x)) +
    geom_tile(width = .8, height = .8) +
    scale_y_discrete(limits = letters[1:6]) +
    coord_fixed() +
    facet_grid(cols = vars(xgrp, x)) + 
    theme(axis.title = element_blank(), 
          axis.ticks.y = element_blank())
  if(data$plotnum != 1)
    p <- p + theme(axis.text.y = element_blank())
  p
}

data %>%
  mutate(
    group = interaction(x, xgrp),
    plotnum = row_number()
  ) %>%
  nest(data = -group) %>%
  mutate(
    plots = map(.x=data, .f=~make_plot(.x))
  ) %>%
  pull(plots) %>%
  wrap_plots(nrow = 1)

[FaizanKhalidMohsin]

I was just wondering is it possible to have this properly fixed?

[baderstine]

as in, restore the previous functionality when the x and y axes are discrete or what?

[Gsmith535]

Yes, please!

[FaizanKhalidMohsin]

@baderstine @Gsmith535
Yes, please, can space = "free" correctly work for facet_grid().