Create custom annotate function

Question

I am struggling to modify ggplot2 annotate(). All I want to do, is create a slightly modified annotate() function (say, annotate_new()) which automatically places annotations in the top left corner with a certain text size.

Below, please find my try which somehow doesn't work:

annotate_new <- 
  function (geom, xmin = NULL, xmax = NULL, 
            ymin = NULL, ymax = NULL, xend = NULL, yend = NULL, 
            x=NULL, y=NULL, parse=TRUE, size = 12, ..., 
            na.rm = FALSE) {
    position <- compact(list(xmin = xmin, xmax = xmax, 
                             xend = xend, ymin = ymin, ymax = ymax, yend = yend,
                             x = -Inf, y = Inf, 
                             hjust = 0, vjust = 1))
    aesthetics <- c(position, list(...))
    lengths <- vapply(aesthetics, length, integer(1))
    n <- unique(lengths)
    if (length(n) > 1L) {
      n <- setdiff(n, 1L)
    }
    if (length(n) > 1L) {
      bad <- lengths != 1L
      details <- paste(names(aesthetics)[bad], " (", 
                       lengths[bad], ")", sep = "", collapse = ", ")
      stop("Unequal parameter lengths: ", details, call. = FALSE)
    }
    data <- vctrs::new_data_frame(position, n = n)
    layer(geom = "text", 
          params = list(na.rm = na.rm, ...), stat = StatIdentity, 
          position = PositionIdentity, data = data, mapping = aes_all(names(data)), 
          inherit.aes = FALSE, show.legend = FALSE)
  }


ggplot(mpg, aes(displ, hwy)) + 
  geom_point() + 
  annotate_new(label = corr_eqn(mpg$hwy, mpg$displ))

This creates:

Somehow, the text size isn't adjustable... Would really appreciate your help!

Rather than trying to create a new annotation style, why don't you put your formatted figure in its own function so you call your_plot_function(x,y,labelx, labely, annotation) and it produces your figure? — melmo
– melmo, Commented May 19, 2020 at 12:35
because I would use this function over and over again (for several hundred plots) — BeSeLuFri
– BeSeLuFri, Commented May 19, 2020 at 12:41

Mohanasundaram · Accepted Answer · 2020-05-19 13:50:27Z

In your code, call size in the list of parmeters

annotate_new <- 
  function (geom, xmin = NULL, xmax = NULL, 
            ymin = NULL, ymax = NULL, xend = NULL, yend = NULL, 
            x=NULL, y=NULL, parse=TRUE, size = 12, ..., 
            na.rm = FALSE) {
    position <- compact(list(xmin = xmin, xmax = xmax, 
                             xend = xend, ymin = ymin, ymax = ymax, yend = yend,
                             x = -Inf, y = Inf, 
                             hjust = 0, vjust = 1))
    aesthetics <- c(position, list(...))
    lengths <- vapply(aesthetics, length, integer(1))
    n <- unique(lengths)
    if (length(n) > 1L) {
      n <- setdiff(n, 1L)
    }
    if (length(n) > 1L) {
      bad <- lengths != 1L
      details <- paste(names(aesthetics)[bad], " (", 
                       lengths[bad], ")", sep = "", collapse = ", ")
      stop("Unequal parameter lengths: ", details, call. = FALSE)
    }
    data <- vctrs::new_data_frame(position, n = n)
    layer(geom = "text", 
          params = list(na.rm = na.rm, size = size, ...), stat = StatIdentity, 
          position = PositionIdentity, data = data, mapping = aes_all(names(data)), 
          inherit.aes = FALSE, show.legend = FALSE)
  }


ggplot(mpg, aes(displ, hwy)) + 
  geom_point() + 
  annotate_new(label = "temp", size = 13)

bs93 · Accepted Answer · 2020-05-19 15:40:28Z

1

Instead of re-writing the source code would you be open to creating a wrapper for the annotate function?

annotate_new <- function(...){
  annotate('text',
           x = -Inf,
           y = Inf,
           size = 12, 
           hjust = 0,
           vjust = 1,
           ...)
}

ggplot(mpg, aes(displ, hwy)) + 
  geom_point()+
  annotate_new(label="Label")

This is the same function with some of your preferred defaults set and you can still pass through additional arguments via the '...' like the 'label'.

edited May 19, 2020 at 15:40

answered May 19, 2020 at 13:40

bs93

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1 Comment

BeSeLuFri Over a year ago

While the answer above is the correct one to my question, I love yours and will use it. I somewhat stupidly didn't think about creating a wrapper on the function. Thank you

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