ggplot2 : How to reduce the width AND the space between bars with geom_bar

Question

I understand that one can change the width of a bar in geom_bar using the width argument. That does work, but then it creates a larger gap between the bars. Is there a way to manually push the bars closer to together? Should I be manipulating the axis somehow instead?

Here is an example, changing width to 0.3 on the right to get the desired bar width.

library(tidyverse)
library(gridExtra)

p1 <- ggplot(iris, aes(Species, Petal.Length)) + geom_bar(stat="summary")
p2 <- ggplot(iris, aes(Species, Petal.Length)) + geom_bar(stat="summary", width=0.3)
grid.arrange(p1,p2,nrow=1)

Note: I know this question is similar to this one, but the answer to closing the gap was not apparent.

How to change the space between bars in geom_bar?

Answer 1

I would adjust the plot's aspect ratio, and have ggplot automatically assign the right width for the bars and the gap between them:

  ggplot(iris, aes(Species, Petal.Length)) + 
      geom_bar(stat="summary", width=0.4) +
      theme(aspect.ratio = 2/1)

Produces this:

Answer 2

Rather than taking the width smaller, which narrows the bars but increases the inter-bar space, set width = 1 to remove all space between.*

ggplot(iris, aes(Species, Petal.Length, fill=Species)) + geom_bar(stat="summary", width=1)

The default value is 0.9, so you can get very small spaces by setting width = 0.95

ggplot(iris, aes(Species, Petal.Length, fill=Species)) + geom_bar(stat="summary", width=0.95)

• With fill=Species, I took the liberty of adding color to help see the different bars when there is no space between.