How to Export a Shapefile as KML Using R

Question

All,

I have exported an ESRI shapefile (polygon) to KML using R, but the resulting layer shows only the outer extent of the polygon. How can I fill in the area with a color? Any help is greatly appreciated.

The code is as follows:

library(rgdal)
setwd("G:\\GIS_SJR\\GIS Shapefiles\\Boundaries")
polygon <- readOGR(".", "20km_buffer_albers")
polygonWGS <- spTransform(polygon, CRS("+proj=longlat +ellps=WGS84 +datum=WGS84"))  
writeOGR(polygonWGS, dsn="polygonWGS.kml", layer="polygonWGS", driver="KML")

Answer 1

As said in the comments above, the Global Soil Information Facilities (tutorials) website maintained, amongst others, by some of the plotKML authors and contributors gives you everything you need to produce filled polygon areas. In addition to the absolutely correct solution by @Nahm above, here's a reproducible example for future queries on the topic.

## required packages
library(rgdal)
library(rworldmap)
library(plotKML)

## shapefile data
data("countriesCoarse")
spy <- subset(countriesCoarse, continent == "Africa")

## plotKML
data("worldgrids_pal")
plotKML(spy["MAP_COLOR"], filename = "africa.kml",
        colour_scale = worldgrids_pal[["lgn3"]])

You may find extra information on further plotKML settings including supported color palettes here.