Drilldown by class group in HighcharteR - R

Question

I have this data:

library(highcharter) 
library(dplyr)

the_dates <- as.Date(c(rep("2021-01-01",3),
                       rep("2021-02-01",3)))
the_values <- c(2,3,4,5,6,7)
the_group <- c("Group_A","Group_B","Group_B",
               "Group_A","Group_B","Group_B")
the_class <- c("X","Y","Z",
               "X","Y","Z")

the_data <- data.frame(the_dates,
                       the_group,
                       the_class,
                       the_values,
                       stringsAsFactors = FALSE)
> the_data
   the_dates the_group the_class the_values
1 2021-01-01   Group_A         X          2
2 2021-01-01   Group_B         Y          3
3 2021-01-01   Group_B         Z          4
4 2021-02-01   Group_A         X          5
5 2021-02-01   Group_B         Y          6
6 2021-02-01   Group_B         Z          7

And I want to create a drill down plot. So I would like to see the groups and if I drill down, I would like to see the class. What I have tried is:

the_data %>%
  hchart(
    type = "spline",
    hcaes(x = the_dates, y = the_values, drilldown = the_class),
    colorByPoint = TRUE)

But the link to drill down is in the dates. Any help will be greatly appreciated.

Answer 1

Here's one potential solution with a few caveats.

I had some issues with as.Date() in the drilldown x axis names, so I've left them as characters. I've also done a quick mean() on the the_values by the_date so there's actually something to drilldown to.

library(highcharter) 
library(dplyr)
library(purrr) # for the map() function 

the_dates <- c(rep("2021-01-01",3),
               rep("2021-02-01",3))
the_values <- c(2,3,4,5,6,7)
the_group <- c("Group_A","Group_B","Group_B",
               "Group_A","Group_B","Group_B")
the_class <- c("X","Y","Z",
               "X","Y","Z")

the_data <- data.frame(the_dates,
                       the_group,
                       the_class,
                       the_values,
                       stringsAsFactors = FALSE)

mean_data <- the_data %>% 
  group_by(the_dates) %>% 
  summarise(mean_values = mean(the_values))

drill_data <- the_data %>%
  group_nest(the_dates) %>% 
  mutate(
    id   = the_dates,
    type = "column",
    data = map(data, ~ .x %>%
      mutate(
        name = the_class,
        y    = the_values
      ) %>%
      list_parse())
  )

Now let's build the plot:

mean_data %>%
  hchart(
    type = "spline",
    hcaes(x = the_dates, y = mean_values, drilldown = the_dates, name = the_dates),
    name = "Dates",
    colorByPoint = TRUE) %>% 
  hc_drilldown(
    allowPointDrilldown = TRUE,
    series = list_parse(drill_data)
  )