geojsonio

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Convert various data formats to GeoJSON or TopoJSON

This package is a utility to convert 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:

*json Info

Install

A note about installing rgdal and rgeos - these two packages are built on top of C libraries, and their installation often causes trouble for Mac and Linux users because no binaries are provided on CRAN for those platforms. Other dependencies in geojsonio should install easily automatically when you install geojsonio. Change to the version of rgdal and GDAL you have):

Mac

Install GDAL on the command line first, e.g., using homebrew

brew install gdal

Then install rgdal and rgeos

install.packages("rgdal", 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")
install.packages("rgeos", type = "source")

Linux

Get deps first

sudo apt-get install libgdal1-dev libgdal-dev libgeos-c1 libproj-dev

Then install rgdal and rgeos

install.packages("rgdal", type = "source")
install.packages("rgeos", type = "source")

Install geojsonio

Stable version from CRAN

install.packages("geojsonio")

Or development version from GitHub

install.packages("devtools")
devtools::install_github("ropensci/geojsonio")
library("geojsonio")

GeoJSON

Convert various formats to GeoJSON

From a numeric vector of length 2, as json or list

geojson_json(c(32.45, -99.74))
#> <FeatureCollection> 
#>   type:  FeatureCollection 
#>   no. features:  1 
#>   features (1st 5):  Point
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

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
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 list

geojson_list(sp_poly)$features[[1]]
#> $type
#> [1] "Feature"
#> 
#> $id
#> [1] 1
#> 
#> $properties
#> $properties$dummy
#> [1] 0
#> 
...

Combine objects

geo_list + geo_list

Note: geo_list is the output type from geojson_list(), it’s just a list with a class attached so we know it’s geojson :)

vec <- c(-99.74, 32.45)
a <- geojson_list(vec)
vecs <- list(c(100.0, 0.0), c(101.0, 0.0), c(100.0, 0.0))
b <- geojson_list(vecs, geometry = "polygon")
a + b
#> $type
#> [1] "FeatureCollection"
#> 
#> $features
#> $features[[1]]
#> $features[[1]]$type
#> [1] "Feature"
#> 
#> $features[[1]]$geometry
#> $features[[1]]$geometry$type
...

json + json

c <- geojson_json(c(-99.74, 32.45))
vecs <- list(c(100.0, 0.0), c(101.0, 0.0), c(101.0, 1.0), c(100.0, 1.0), c(100.0, 0.0))
d <- geojson_json(vecs, geometry = "polygon")
c + d
#> {"type":"FeatureCollection","features":[{"type":"Feature","geometry":{"type":"Point","coordinates":[-99.74,32.45]},"properties":{}},{"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[100,0],[101,0],[101,1],[100,1],[100,0]]]},"properties":[]}]}

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

file <- system.file("examples", "california.geojson", package = "geojsonio")
out <- geojson_read(file)
names(out)
#> [1] "type"     "crs"      "features"
names(out$features[[1]])
#> [1] "type"       "_id"        "properties" "geometry"

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 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$geometries[[1]]$id
#> [1] 1
#> 
#> $objects$foo$geometries[[1]]$properties
...

Write TopoJSON

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

Read TopoJSON

library("sp")
url <- "https://raw.githubusercontent.com/shawnbot/d3-cartogram/master/data/us-states.topojson"
out <- topojson_read(url, verbose = FALSE)
plot(out)
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Use case: Play with US states

Using data from https://github.com/glynnbird/usstatesgeojson

Get some geojson

library('httr')
res <- GET('https://api.github.com/repos/glynnbird/usstatesgeojson/contents')
st_names <- Filter(function(x) grepl("\\.geojson", x), sapply(content(res), "[[", "name"))
base <- 'https://raw.githubusercontent.com/glynnbird/usstatesgeojson/master/'
st_files <- paste0(base, st_names)

Make a faceted plot

library('ggplot2')
library('plyr')
st_use <- st_files[7:13]
geo <- lapply(st_use, geojson_read, method = "local", what = "sp")
df <- ldply(setNames(lapply(geo, fortify), gsub("\\.geojson", "", st_names[7:13])))
ggplot(df, aes(long, lat, group = group)) +
  geom_polygon() +
  facet_wrap(~.id, scales = "free")
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Okay, so the maps are not quite right (stretched to fit each panel), but you get the idea.

GeoJSON <-> TopoJSON

geo2topo() and topo2geo()

x <- '{"type": "LineString", "coordinates": [ [100.0, 0.0], [101.0, 1.0] ]}'
(topo_json <- geo2topo(x))
#> {"type":"Topology","objects":{"foo":{"type":"LineString","arcs":[0]}},"arcs":[[[100,0],[101,1]]],"bbox":[100,0,101,1]}
topo2geo(topo_json)
#> OGR data source with driver: GeoJSON 
#> Source: "{"type":"Topology","objects":{"foo":{"type":"LineString","arcs":[0]}},"arcs":[[[100,0],[101,1]]],"bbox":[100,0,101,1]}", layer: "TopoJSON"
#> with 1 features
#> It has 1 fields
#> <FeatureCollection> 
#>   type:  FeatureCollection 
#>   no. features:  1 
#>   features (1st 5):  LineString

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