Count labels for `geom_histogram()` are sometimes type `double`

[IndrajeetPatil]

Since counts are always integers, I would have expected that the x-axis labels for geom_histogram() to be always of type integer.

But this seems to be the case only when set.seed() is used, if the histogram is for randomly generated data.

Is this expected behavior?

without set.seed()

library(ggplot2)

histData1 <- data.frame(x = rnorm(100))

ggplot(histData1, aes(x)) +
  geom_histogram(color = "black") 
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

with set.seed()

set.seed(123)
histData2 <- data.frame(x = rnorm(100))

ggplot(histData2, aes(x)) +
  geom_histogram(color = "black") 
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

^{Created on 2022-03-04 by the reprex package (v2.0.1.9000)}

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[yutannihilation]

The continuous scale is always double, so this is the expected behavior, unfortunately.

But this seems to be the case only when set.seed() is used, if the histogram is for randomly generated data.

No, it simply depends on what seed you use.

library(ggplot2)

set.seed(190)
histData2 <- data.frame(x = rnorm(100))

ggplot(histData2, aes(x)) +
  geom_histogram(color = "black") 
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

^{Created on 2022-03-05 by the reprex package (v2.0.1)}

[IndrajeetPatil]

I see. Thanks!

Do you think that this is something that should be reflected in the docs for geom_histogram()?

Not a single example in the docs have fractional counts; all of them are integers.

This is why, when I see fractional counts as axes labels, my first thought isn't "This must be a ggplot limitation", but rather "I must be doing something wrong" or "Something is amiss with my data".

It would be reassuring to have this behavior documented.

[yutannihilation]

Do you think that this is something that should be reflected in the docs for geom_histogram()?

I personally don't think so. I agree the docs could help you a bit better, but I feel geom_histogram() is not the right place because it's about behavior of the scale.

FYI, probably this is what you want:

https://scales.r-lib.org/reference/breaks_extended.html

[iagogv3]

Looking for something similar (integer breaks for an integer variable), I arrived here. Thanks, @yutannihilation, for telling about breaks_extended. However, it breaks yet on non-integer values (of course, depending on the given n, but it may be the default one).

On https://scales.r-lib.org/reference/breaks_pretty.html it says that

This is primarily useful for date/times, as extended_breaks() should do a slightly better job for numeric scales.

but in this case, breaks_pretty prints integer values, so it does a better job here.

Wouldn't make sense to define something like scale_x_integer and so...?