geojsonio vignette

Scott Chamberlain

2024-11-27

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:

• geojson_list()/topojson_list() - convert to GeoJSON/TopoJSON as R list format
• geojson_json()/topojson_json() - convert to GeoJSON/TopoJSON as JSON
• geojson_sp() - convert output of geojson_list() or geojson_json() to spatial objects
• geojson_read()/topojson_read() - read a GeoJSON/TopoJSON file from file path or URL
• geojson_write()/topojson_write() - write a GeoJSON/TopoJSON file locally

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

Additional functions:

• map_gist() - push up a geojson or topojson file as a GitHub gist (renders as an interactive map) - See the maps with geojsonio vignette.
• map_leaf() - create a local interactive map with the leaflet package - See the maps with geojsonio vignette.

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

remotes::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))
#> <FeatureCollection> 
#>   type:  FeatureCollection 
#>   no. features:  1 
#>   features (1st 5):  Point

as a list

geojson_list(c(32.45, -99.74))
#> $type
#> [1] "FeatureCollection"
#> 
#> $features
#> $features[[1]]
#> $features[[1]]$type
#> [1] "Feature"
#> 
#> $features[[1]]$geometry
#> $features[[1]]$geometry$type
...

From a data.frame

as json

library('maps')
data(us.cities)
geojson_json(us.cities[1:2, ], lat = 'lat', lon = 'long')
#> <FeatureCollection> 
#>   type:  FeatureCollection 
#>   no. features:  2 
#>   features (1st 5):  Point, Point

as a list

geojson_list(us.cities[1:2, ], lat = 'lat', lon = 'long')
#> $type
#> [1] "FeatureCollection"
#> 
#> $features
#> $features[[1]]
#> $features[[1]]$type
#> [1] "Feature"
#> 
#> $features[[1]]$geometry
#> $features[[1]]$geometry$type
...

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)
#> <FeatureCollection> 
#>   type:  FeatureCollection 
#>   no. features:  2 
#>   features (1st 5):  Polygon, Polygon

to a list

geojson_list(sp_poly)
#> $type
#> [1] "FeatureCollection"
#> 
#> $name
#> [1] "file105948c0b90f"
#> 
#> $features
#> $features[[1]]
#> $features[[1]]$type
#> [1] "Feature"
...

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)
#> <FeatureCollection> 
#>   type:  FeatureCollection 
#>   no. features:  5 
#>   features (1st 5):  Point, Point, Point, Point, Point

to a list

geojson_list(s)
#> $type
#> [1] "FeatureCollection"
#> 
#> $name
#> [1] "file105946b2103a"
#> 
#> $features
#> $features[[1]]
#> $features[[1]]$type
#> [1] "Feature"
...

Write geojson

library('maps')
data(us.cities)
geojson_write(us.cities[1:2, ], lat = 'lat', lon = 'long')
#> <geojson-file>
#>   Path:       myfile.geojson
#>   From class: data.frame

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))
#> {"type":"Topology","objects":{"foo":{"type":"GeometryCollection","geometries":[{"type":"Point","coordinates":[-99.74,32.45]}]}},"arcs":[],"bbox":[-99.74,32.45,-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)
#> $type
#> [1] "Topology"
#> 
#> $objects
#> $objects$foo
#> $objects$foo$type
#> [1] "GeometryCollection"
#> 
#> $objects$foo$geometries
#> $objects$foo$geometries[[1]]
#> $objects$foo$geometries[[1]]$type
#> [1] "Point"
#> 
#> $objects$foo$geometries[[1]]$coordinates
#> [1] 1 3
#> 
#> $objects$foo$geometries[[1]]$properties
#> $objects$foo$geometries[[1]]$properties$dat
#> [1] 1
#> 
...

Read from a file

file <- system.file("examples", "us_states.topojson", package = "geojsonio")
out <- topojson_read(file)
summary(out)
#>       id                    geometry 
#>  Length:51          MULTIPOLYGON:51  
#>  Class :character   epsg:NA     : 0  
#>  Mode  :character

Read from a URL

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

Or use as.location() first

(loc <- as.location(file))
#> <location> 
#>    Type:  file 
#>    Location:  /usr/local/lib/R/site-library/geojsonio/examples/us_states.topojson
out <- topojson_read(loc)