removing space between ggrepel label made using plotmath

Question

I am creating a plot where I want to display labels using ggrepel. I am showing a minimal example below that illustrates how the label has two components separated by a comma - first related to the type of iris flower species and the second to the sample size for that group.

# needed libraries
set.seed(123)
library(ggrepel)

# creating a dataframe with label column
(df <- iris %>%
  dplyr::group_by(Species) %>%
  dplyr::summarise(n = n(), mean = mean(Sepal.Length)) %>%
  purrrlyr::by_row(
    .d = .,
    ..f = ~ paste("list(~",
                  .$Species,
                  ",",
                  .$n,
                  ")",
                  sep = ""),
    .collate = "rows",
    .to = "label",
    .labels = TRUE
  ))
#> # A tibble: 3 x 4
#>   Species        n  mean label               
#>   <fct>      <int> <dbl> <chr>               
#> 1 setosa        50  5.01 list(~setosa,50)    
#> 2 versicolor    50  5.94 list(~versicolor,50)
#> 3 virginica     50  6.59 list(~virginica,50)

# displaying labels
ggplot(iris, aes(Species, Sepal.Length)) +
  geom_point() +
  ggrepel::geom_label_repel(data = df,
                            aes(x = Species, y = mean, label = label),
                            parse = TRUE)

^{Created on 2018-11-17 by the reprex package (v0.2.1)}

My question is how I can get rid of the space between these two components. Although I have specified sep = "" in paste() function, there is still extra space between two components that I don't want (e.g., setosa, 50, versicolor, 50, virginica, 50 labels should instead be setosa,50, versicolor,50, virginica,50).

Answer 1

Below is an updated version of your code, which implements a way to place the comma (without a succeeding space) between the Species name and the sample size. You labels, for example, will look like "~setosa*\",\"*50" instead of list(~setosa,50)

(df <- iris %>%
    dplyr::group_by(Species) %>%
    dplyr::summarise(n = n(), mean = mean(Sepal.Length)) %>%
    purrrlyr::by_row(
      .d = .,
      ..f = ~ paste("~",
                    .$Species,
                    "*\",\"*",
                    .$n,
                    "",
                    sep = ""),
      .collate = "rows",
      .to = "label",
      .labels = TRUE
    ))
#> # A tibble: 3 x 4
#>   Species        n  mean label               
#>   <fct>      <int> <dbl> <chr>               
#> 1 setosa        50  5.01 "~setosa*\",\"*50"
#> 2 versicolor    50  5.94 "~versicolor*\",\"*50"
#> 3 virginica     50  6.59 "~virginica*\",\"*50"


# displaying labels
ggplot(iris, aes(Species, Sepal.Length)) +
  geom_point() +
  stat_smooth(method="lm",size=0.6,se=FALSE,colour="black")+
  ggrepel::geom_label_repel(data = df,
                            aes(x = Species, y = mean, label = label),
                            parse = TRUE)

Which produces the following plot:

Hope it helps.