geojsonio vignette

Scott Chamberlain

2020-02-11

geojsonio converts geographic data to geojson and topojson formats. Nothing else. We hope to do this one job very well, and handle all reasonable use cases.

Functions in this package are organized first around what you’re working with or want to get, geojson or topojson, then convert to or read from various formats:

Each of the above functions have methods for various objects/classes, including numeric, data.frame, list, SpatialPolygons, SpatialLines, SpatialPoints, etc.

Additional functions:

Install

Install rgdal - in case you can’t get it installed from binary , here’s what works on a Mac (change to the version of rgdal and GDAL you have).

install.packages("http://cran.r-project.org/src/contrib/rgdal_1.1-3.tar.gz", repos = NULL, type="source", configure.args = "--with-gdal-config=/Library/Frameworks/GDAL.framework/Versions/1.11/unix/bin/gdal-config --with-proj-include=/Library/Frameworks/PROJ.framework/unix/include --with-proj-lib=/Library/Frameworks/PROJ.framework/unix/lib")

Stable version from CRAN

install.packages("geojsonio")

Development version from GitHub

devtools::install_github("ropensci/geojsonio")
library("geojsonio")

GeoJSON

Convert various formats to geojson

From a numeric vector of length 2

as json

geojson_json(c(32.45, -99.74))

as a list

geojson_list(c(32.45, -99.74))

From a data.frame

as json

library('maps')
data(us.cities)
geojson_json(us.cities[1:2, ], lat = 'lat', lon = 'long')

as a list

geojson_list(us.cities[1:2, ], lat = 'lat', lon = 'long')

From SpatialPolygons class

library('sp')
poly1 <- Polygons(list(Polygon(cbind(c(-100,-90,-85,-100),
  c(40,50,45,40)))), "1")
poly2 <- Polygons(list(Polygon(cbind(c(-90,-80,-75,-90),
  c(30,40,35,30)))), "2")
sp_poly <- SpatialPolygons(list(poly1, poly2), 1:2)

to json

geojson_json(sp_poly)

to a list

geojson_list(sp_poly)

From SpatialPoints class

x <- c(1, 2, 3, 4, 5)
y <- c(3, 2, 5, 1, 4)
s <- SpatialPoints(cbind(x, y))

to json

geojson_json(s)

to a list

geojson_list(s)

Write geojson

library('maps')
data(us.cities)
geojson_write(us.cities[1:2, ], lat = 'lat', lon = 'long')

Read geojson

library("sp")
file <- system.file("examples", "california.geojson", package = "geojsonio")
out <- geojson_read(file, what = "sp")
plot(out)

Topojson

To JSON

topojson_json(c(-99.74,32.45))

To a list

library(sp)
x <- c(1,2,3,4,5)
y <- c(3,2,5,1,4)
s <- SpatialPoints(cbind(x,y))
topojson_list(s)

Read from a file

file <- system.file("examples", "us_states.topojson", package = "geojsonio")
out <- topojson_read(file, verbose = FALSE)
summary(out)

Read from a URL

url <- "https://raw.githubusercontent.com/shawnbot/d3-cartogram/master/data/us-states.topojson"
out <- topojson_read(url, verbose = FALSE)

Or use as.location() first

(loc <- as.location(file))
out <- topojson_read(loc, verbose = FALSE)