Make a choropleth from a non-highmap-collection map - r

Question

I've been trying to make a choropleth map with hcmap from highcharter package; I obtained the polygons from my own shapefile because it's a map that is not on the list of highmap's collection.
To do so, first I managed to transform my shapefile to a GeoJson file, as described here:
https://blog.exploratory.io/creating-geojson-out-of-shapefile-in-r-40bc0005857d
Later I managed to draw the map using the package geosonio as described here:
http://jkunst.com/highcharter/highmaps.html#geojsonio-package
However, I can't figure out how to merge a dataframe with values into the polygons drawn in my map. All the examples availables are merging to mapdata that is in a data.frame format, which I lose when transforming to GeoJson.
Here's my code so far:
library(rgdal)
library(geojsonio)
library(highcharter)
#Get map from shapefile
Mymap <- readOGR(dsn="Mymap", "Mymap", verbose = FALSE) %>%
spTransform(CRS("+proj=longlat +ellps=GRS80 +datum=WGS84"))
#Transform to geoJson
MymapJSON <- geojson_json(Mymap)
#Use geojsonio to make data compatible with hcmap
Myhcmap <- jsonlite::fromJSON(MymapJSON, simplifyVector = FALSE)
Myhcmap<- geojsonio::as.json(Myhcmap)
#Draw map:
highchart(type = "map") %>%
hc_add_series(mapData = Myhcmap, showInLegend = T)
Result:
¿How can I put additional data into the GeoJson so I can draw a choropleth?

Answer 1

I finally got to a solution by myself some time ago, it's was fairly simple but since it's not well documented how to add data to the GeoJSON, I will show it here:
#Work with the map until this step:
Myhcmap <- jsonlite::fromJSON(MymapJSON, simplifyVector = FALSE)
#This part was unnecessary:
#Myhcmap<- geojsonio::as.json(Myhcmap)
#Then, write your map like this:
highchart() %>%
hc_add_series_map(Myhcmap, df, value = "value", joinBy = "ID")
Where:
dfis the dataframe you want to append
value is the column name of the data you want to color your map by
joinBy is the joining key variable