ggtitle overwrites subtitle

[ptoche]

Not a big deal: ggtitle() overwrites subtitle

ggplot(data=mtcars, aes(x=mpg, y=cyl)) + geom_point() + labs(title="title", subtitle="subtitle")
p = last_plot()
p + ggtitle("title2")  # overwrites subtitle
p + labs(title="title2")  # does not overwrite subtitle

Below I tried to use reprex(clipr::read_clip()), but it doesn't seem to work too well...

#> [1] "library(ggplot2)"
#> [2] "ggplot(data=mtcars, aes(x=mpg, y=cyl)) + geom_point() + labs(title="title", subtitle="subtitle")"
#> [3] "p = last_plot()"
#> [4] "p + ggtitle("title2") # overwrites subtitle"
#> [5] "p + labs(title="title2") # does not overwrite subtitle"

[DarioBoh]

ggtitle default for the argument subtitle is NULL

[batpigandme]

As @DarioBoh mentioned, the default arg in ggtitle for subtitle is NULL (it's even in bold in the docs for it 😉). So, you're basically overwriting the whole "title" entity (subtitle absence and all) in the second plot.

library(ggplot2)
ggplot(data=mtcars, aes(x=mpg, y=cyl)) + geom_point() + labs(title="title", subtitle="subtitle")

p <- last_plot()
p + ggtitle("title2")  # overwrites subtitle

p + ggtitle("title2", subtitle = "subtitle")  # overwrites subtitle

p + labs(title="title2")  # does not overwrite subtitle

Created on 2018-02-12 by the reprex package (v0.2.0).

[ptoche]

I may have been misunderstood. I understand the reasons why ggtitle() overwrites subtitle. I just don't think it's a natural state of affairs and would find it more logical if it didn't. Either ggtitle() is retired in favour of labs() or a ggsubtitle() is added, ensuring that ggtitle ceases to overwrite the subtitle.

If the function was named ggtitles() with an s, it wouldn't bother me.

ggsubtitle <- function(x) {
    return(labs(subtitle = x))
}

[batpigandme]

I guess the order of operations of having a title and subtitle written using labs() and then subsequently adding a ggtitle() with just a title (no subtitle) seems like an edge case to me. But, as always n = 1. Changing it to ggtitles() would involve deprecating ggtitle(), so that's also a downside.

An easier option would be to clarify what will happen in the docs— though it does already say that the subtitle defaults to NULL.

As you can see below, the layered nature of things means that if you add a subtitle using labs() after using ggtitle() nothing is overwritten, but, again, that's definitely not how my workflow would go.

library(ggplot2)
p <- ggplot(data = mtcars, aes(x = mpg, y = cyl)) +
  geom_point()


p + 
  ggtitle("title") + 
  labs(subtitle = "subtitle")

Created on 2018-02-14 by the reprex package (v0.2.0).

[lock]

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