R: Highchart map is blank

Question

I'm trying to plot the frequency of words on a map with bubbles. I'm using my API in order to import the data - then I'm counting and merging and then I'm trying to plot. Everything works fine, except that the map output is blank. This is the code I have:

library(httr)
library(jsonlite)
library(stringr)
library(highcharter)
library(dplyr)
library(highcharter)
library(tidytext)

zählen <- function(data, word) {
  result_grouped <- group_by(data, id, year, autor)
  result <- summarise(result_grouped, count = str_count(text, word))

  return(result)
}

res <- POST('https://api.textminr.tech/getTextByYearBetween/?minYear=1800&maxYear=1900')
data <- fromJSON(rawToChar(res$content))

data$lat <- NA
data$long <- NA

for (i in 1:nrow(data)) {
  author <- data$author[i]
  formatted <- URLencode(author)
  formatted_author <- gsub(",", "%2C", formatted)
  
  try({
    author_url <- str_glue('https://api.textminr.tech/getBirthplaceOfAuthor/?authorname={formatted_author}')
    res <- POST(author_url)
    authorData <- fromJSON(rawToChar(res$content))
  
    data$lat[i] <- authorData$lat
    data$long[i] <- authorData$long
  }, silent = TRUE)
}

# Ensure that lat and long are numeric
data$lat <- as.numeric(data$lat)
data$long <- as.numeric(data$long)

# Count the frequency of the word "war" in each text
word_counts <- data %>%
  unnest_tokens(word, text) %>%
  count(id, word) %>%
  filter(str_to_lower(word) == "war") %>%
  left_join(data, by = "id") %>%
  mutate(frequency = n)

# Create a list that highcharter can work with
map_data <- word_counts %>%
  mutate(name = author) %>%
  select(name, lat, long, frequency) %>%
  list_parse()

# Create the map
wmap <- highchart() %>% 
  hc_add_series(
    data = map_data,
    type = "mapbubble",
    name = "Word Frequency",
    maxSize = '10%'
  ) %>%
  hc_mapNavigation(enabled = TRUE)

# Print the map
wmap

The API should be open to anyone in case you need to test the functionality.

I also tried an example code, where I encounter the same issue - the output is blank:

library(highcharter)
library(dplyr)

# Here's some example data with countries and values
data_countries <- data.frame(
  code = c('DE', 'US', 'FR', 'ES', 'IT'),
  value = c(4, 5, 3, 7, 6)
)

# First, let's get the map data for the world
data_world <- get_data_from_map(download_map_data('custom/world'))

# Now, let's create the highchart map
highchart(type = "map") %>% 
  hc_add_series(data = data_world, mapData = data_world, joinBy = "hc-key", name = "Basemap") %>% 
  hc_add_series(data = data_countries, type = "mapbubble", mapData = data_world, joinBy = c("iso-a2", "code"), name = "Countries", maxSize = '12%') %>% 
  hc_mapNavigation(enabled = TRUE) # Add navigation buttons

Answer 1

The are several issues with your code. First, to get the map data use download_map_data("custom/world"). get_data_from_map is only useful to extract any data from this map but is of no use to draw the map. In the docs it is used to create example data. You also have to make sure that you specify the right joinBy column. Next, if you want a choropleth map you have to map a column on value=.

And if you want a bubble map then you need different data. As the bubble is drawn on a point you need data containing latitude and longitude.

Here are working examples based for both cases:

library(highcharter)

# Here's some example data with countries and values
data_countries <- data.frame(
  code = c("DE", "US", "FR", "ES", "IT"),
  value = c(4, 5, 3, 7, 6)
)

map <- download_map_data("custom/world")

highchart(type = "map") |> 
  hc_add_series_map(
    map = map,
    df = data_countries, 
    value = "value",
    joinBy = c("hc-a2", "code"), 
    name = "Countries"
  ) %>%
  hc_mapNavigation(enabled = TRUE)

# Bubble map
data_bubble <- data.frame(
  name = c("IT", "FR"),
  lat = c(41.89333, 48.856667),
  lon = c(12.48778, 2.351667),
  z = c(2, 2)
)

highchart(type = "map") |> 
  hc_add_series(
    mapData = map,
    name = "Basemap"
  ) %>%
  hc_add_series(
    data = data_bubble, 
    type = "mapbubble",
    name = "Countries", 
    maxSize = "12%"
  ) %>%
  hc_mapNavigation(enabled = TRUE)