Using coord_fixed() in Facetted ggplot Creates White Space Above and Below the Plot in Rmarkdown (html, Pdf and doc)

Are you tired of dealing with unwanted white space above and below your facetted ggplot plots in Rmarkdown? You’re not alone! One of the most common issues with using coord_fixed() in facetted ggplots is the pesky white space that seems to appear out of nowhere. But fear not, dear reader, for we’ve got the solution right here!

The Problem: Unwanted White Space

When using coord_fixed() in facetted ggplots, you might notice that there’s an annoying amount of white space above and below your plot. This can be frustrating, especially if you’re trying to create a publication-quality document or presentation. The white space can make your plot look awkward and unprofessional.

library(ggplot2)
library(gridExtra)

# Create a sample dataset
df <- data.frame(x = c(1, 2, 3, 4, 5),
                 y = c(2, 4, 6, 8, 10),
                 group = c("A", "B", "A", "B", "A"))

# Create a facetted ggplot with coord_fixed()
p <- ggplot(df, aes(x, y)) +
  geom_point() +
  facet_wrap(~ group, scales = "free") +
  coord_fixed(ratio = 1)

# Print the plot
p

As you can see, the resulting plot has a lot of unwanted white space above and below it. This can be especially problematic if you're trying to fit multiple plots on a single page or slide.

The Solution: Understanding coord_fixed()

So, what's going on with coord_fixed()? Why does it create all that white space? The answer lies in how coord_fixed() works.

coord_fixed() is a ggplot2 coordinate system that fixes the aspect ratio of your plot. This means that the x and y axes are scaled equally, which is useful for creating square or rectangular plots. However, when you use coord_fixed() in a facetted ggplot, the aspect ratio is applied to each individual facet, rather than the entire plot.

This means that even if your facets have different numbers of rows and columns, they'll all be scaled equally, resulting in white space above and below each facet.

Removing White Space with Scales = "fixed"

One way to remove the white space is to use scales = "fixed" instead of scales = "free" in your facet_wrap() or facet_grid() function. This tells ggplot to use a single scale for all facets, rather than individual scales for each facet.

p <- ggplot(df, aes(x, y)) +
  geom_point() +
  facet_wrap(~ group, scales = "fixed") +
  coord_fixed(ratio = 1)

p

As you can see, this gets rid of the white space above and below the plot. However, it also means that the x and y axes are no longer scaled equally, which might not be desirable in all cases.

Removing White Space with Space = "free"

Another way to remove the white space is to use space = "free" in your facet_wrap() or facet_grid() function. This tells ggplot to remove any extra space around each facet.

p <- ggplot(df, aes(x, y)) +
  geom_point() +
  facet_wrap(~ group, scales = "free", space = "free") +
  coord_fixed(ratio = 1)

p

This method also gets rid of the white space, but it can be more flexible than using scales = "fixed", since it allows for different scales in each facet.

Using ggsave() to Remove White Space

Another way to remove white space is to use the ggsave() function from the ggplot2 package. This function allows you to save your plot as an image file, with customizable width, height, and resolution.

ggsave("plot.png", p, width = 6, height = 4, dpi = 300)

As you can see, this saves the plot as a PNG image file with a width of 6 inches, a height of 4 inches, and a resolution of 300 dpi. The resulting image file will not have any white space around it.

Conclusion

In conclusion, removing white space around facetted ggplots with coord_fixed() can be a bit tricky, but it's definitely doable. By understanding how coord_fixed() works and using the right combination of scales, space, and ggsave() functions, you can create beautiful, professional-looking plots that are free of unwanted white space.

Remember, practice makes perfect, so don't be afraid to experiment with different methods and techniques until you find what works best for you. Happy plotting!

Solution	Method	Pros	Cons
scales = "fixed"	Uses a single scale for all facets	No white space, equal axis scaling	Individual facets may not have optimal scaling
space = "free"	Removes extra space around each facet	Flexible, allows for different scales in each facet	May not work well with complex plots or multiple facets
ggsave()	Saves plot as an image file with customizable dimensions	Complete control over plot dimensions, no white space	Requires manual specification of dimensions, may not be suitable for dynamic reports

Which method do you prefer? Do you have any other tips or tricks for removing white space from facetted ggplots? Share your thoughts in the comments below!

Further Reading

• coord_fixed() documentation
• facet_wrap() documentation
• ggsave() documentation
• Facetting with ggplot2

Thanks for reading, and happy plotting!

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