ggplot2 bar chart won't display spaces between bars

Question

I'm trying to create a bar chart in ggplot2 showing a histogram for a large data set.

ggplot(data = score.data, aes(x = score)) + geom_bar(binwidth = .25, width=.9)

My employer's graphic design policy is to have a small amount of separation between bars. But no matter what I set the width parameter to, the plot is generated with no space between bars whatsoever. Is there a different parameter I should be using to accomplish this?

EDIT: Following jeremycg's suggestion in the comments, I've included some of my data.

score <- c(6.25, 4.75, 6, 1.5, 6, 5, 6, 2.75, 6, 2.5, 5.25, 6, 3.75, 6, 
           6.25, 5, 6.75, 2, 2.75, 3.25, 5.625, 6.5, 4, 5, 3)

I'd convert it to a factor, except I want to show bins of size .25 - there are a small number of values between the quarters (as you can see above, where one value is 5.625). And stat_bin only works for data that ggplot thinks is continuous.

The solution depends on the format of your data (factors, numeric, etc). You could try including some of you data in the question - try pasting in the output of dput(head(score.data)). If you have integers as your score, you could try ggplot(data = score.data, aes(x = factor(score))) + geom_bar() — jeremycg
As you haven't responded to my answer yet, I was wondering whether it gave the needed solution for you. — Jaap
Yes, that turned out to work well for what I needed to do. Thank you. — Empiromancer

Jaap Jaap · Accepted Answer · 2015-10-15T18:12:14

Supposing you have numeric data and not integers, you can set colour = "white" and size = 1.5 (or another value) in geom_bar or geom_histogram. This will make the edges of the bars white and thicker (with the size parameter), thus creating some visual space between them:

# create some sample data
set.seed(2)
data <- data.frame(score=rnorm(1000,0,5), int.score=sample(1:10,1000,replace=TRUE))

# create the plot
ggplot(data, aes(x = score)) + 
  geom_bar(binwidth = .25, color="white", size=1.5) +
  theme_bw()

this gives:

When you have integers, you can also use the trick metioned by @jeremycg in the comments:

ggplot(data, aes(x = factor(int.score))) + 
  geom_bar(width=0.7) +
  theme_bw()

which gives:

ggplot2 bar chart won't display spaces between bars

1 Answers