Label limits

[lukauskas]

Implements custom limits for label limits as discussed in #66 .
Takes the parameters limits.x and limits.y to be a vector with two elements, the first one being the lower limit, and the other one being the higher one.
The vectors are in data coordinates.
NAs in the vector are replaced to the image lower or upper bounds respectively.

Usage example:

library(ggrepel)
set.seed(42)
data <- mtcars
mu <- mean(data$wt)

left <- data[data$wt < mu,]
right <- data[data$wt >= mu,]

ggplot(data) +
  geom_vline(aes(xintercept=mu)) +
  geom_point(aes(wt, mpg), color = 'red') +
  geom_text_repel(aes(wt, mpg, label = rownames(left), colour='Left half'),
                  data=left,
                  limits.x=c(NA, mu)) +
  geom_text_repel(aes(wt, mpg, label = rownames(right), colour='Right half'),
                  data=right,
                  limits.x=c(mu, NA)) +
  theme_classic(base_size = 16)

ggsave('example.png')

Result:

[slowkow]

This is great! I have a few requests before I merge this into the master branch:

• To be consistent with ggplot2, use xlim and ylim instead of limits.x and limits.y. For example, xlim and ylim are used in ggplot2::coord_cartesian().

• Both geom_text_repel and geom_label_repel should have this feature.

• Add an example to vignettes/ggplot2.Rmd that demonstrates the usage of this feature.

Please paste this code into the vignettes/ggplot2.Rmd file. Try to describe your feature.

### Limit labels to a specific area

TODO: Write a 1-2 sentence description of what this feature is about.

```{r label-limits, echo=TRUE, fig.width=9, fig.height=7}
set.seed(42)
data <- mtcars
mu <- mean(data$wt)

left <- data[data$wt < mu,]
right <- data[data$wt >= mu,]

ggplot() +
  geom_vline(xintercept = mu) +
  geom_point(
    data = data,
    mapping = aes(wt, mpg)
  ) +
  geom_text_repel(
    data = left,
    mapping = aes(wt, mpg, label = rownames(left), colour = 'Left half'),
    limits.x = c(NA, mu)
  ) +
  geom_text_repel(
    data = right,
    mapping = aes(wt, mpg, label = rownames(right), colour = 'Right half'),
    limits.x = c(mu, NA)
  ) +
  theme_classic(base_size = 16)
```

[lukauskas]

Have a look now, I think this ticks off everything on your TODO list.

[slowkow]

Great work, thank you! I just made some minor changes and merged your commit. You're now a contributor 👍

[lukauskas]

Thanks!

And hehe, was not expecting to appear in the description. :)