rCharts GeoJSON - Change fill color of polygons - json

Question

I'm using rCharts Leaflet maps to display polygons on map on R.
Using the Leaflet's geoJson I created some polygons and added them to the map. However, those polygons are filled with a default blue color. I'm trying to give them a different color, but no success.
For an example, I used the folloeing JSON, tested it in geojson.io and it came up green, however the R package still plots it in blue, how can I enforce the color?
JSON:
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {
"stroke": "#555555",
"stroke-width": 2,
"stroke-opacity": 1,
"fill": "#00f900",
"fill-opacity": 0.5
},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
-74.06982421875,
40.64730356252251
],
[
-74.06982421875,
40.79717741518769
],
[
-73.80615234375,
40.79717741518769
],
[
-73.80615234375,
40.64730356252251
],
[
-74.06982421875,
40.64730356252251
]
]
]
}
}
]
}
R:
jsonx <- (JSON above)
polys = RJSONIO::fromJSON(jsonX)
map.center <- c(38,-95)
myMap<-Leaflet$new()
myMap$setView(map.center, 4)
myMap$tileLayer(provider = "Esri.WorldGrayCanvas")
myMap$geoJson(polys)
myMap$set(dom = 'myChart2')
myMap

Answer 1

While the rCharts implementation was nice, RStudio's leaflet package based on htmlwidgets is much more full-featured and robust. If you can use it instead, here is an answer. Note, nothing needs to be done. leaflet will pick up the fill in your geoJSON.
# uncomment to install the most recent from github
# devtools::install_github("rstudio/leaflet")
# or older cran #install.packages("leaflet")
library(leaflet)
gj <- '
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {
"stroke": "#555555",
"stroke-width": 2,
"stroke-opacity": 1,
"fill": "#00f900",
"fill-opacity": 0.5
},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
-74.06982421875,
40.64730356252251
],
[
-74.06982421875,
40.79717741518769
],
[
-73.80615234375,
40.79717741518769
],
[
-73.80615234375,
40.64730356252251
],
[
-74.06982421875,
40.64730356252251
]
]
]
}
}
]
}
'
leaflet() %>%
addTiles() %>%
setView( -74.1, 40.7, zoom = 10) %>%
addGeoJSON( gj )
# to show fill works let's change it with gsub
leaflet() %>%
addTiles() %>%
setView( -74.1, 40.7, zoom = 10) %>%
addGeoJSON(
gsub(
x = gj
,pattern = '(\\"fill\": \\"#00f900\\",)'
,replacement = ""
)
# demo addGeoJSON fillColor argument
,fillColor = 'green'
)