How can I export a GeoJSON file from R?

Question

The write. function allows one to export a JSON file, but it does not seem to work for a GeoJSON file.

This is the code i ran:

write(map,"Map Layer2.GeoJSON")

and this was the error produced:

Error in cat(list(...), file, sep, fill, labels, append) : 
  argument 1 (type 'S4') cannot be handled by 'cat'

Answer 1

write is just a wrapper for cat (package base). See ?write:

Write Data to a File

Description

The data (usually a matrix) x are written to file file. If x is a two-dimensional matrix you need to transpose it to get the columns in file the same as those in the internal representation.

To write a GeoJSON file, you can use writeOGR() instead (package rgdal):

library("rgdal")
data(meuse)
coordinates(meuse) = c("x", "y")
class(meuse)
# [1] "SpatialPointsDataFrame"
writeOGR(meuse, "test_geojson", layer="meuse", driver="GeoJSON")

Answer 2

Just to clarify rcs great answer and Matt's question for beginners. The dsn should be the path and full file name, layer is required but ignored. No, not sure why.

library("rgdal")
data(meuse)
coordinates(meuse) = c("x", "y")
writeOGR(meuse, dsn="path/test_geojson.GeoJSON", layer="meuse", driver="GeoJSON")

Answer 3

2021 Solution with the sf package

library(sf)
library(rgdal)
data(meuse)
meuse_sf = st_as_sf(meuse, coords = c("x", "y"), crs = 28992, agr = "constant")
st_write(meuse_sf, "meuse.geojson")