GeoJSON.jl
This library is developed independently of, but is heavily influenced in design by the python-geojson package. It contains:
- Functions for encoding and decoding GeoJSON formatted data
- a type hierarchy (according to the GeoJSON specification)
- An implementation of the geo_interface, a GeoJSON-like protocol for geo-spatial (GIS) vector data.
Installation
Pkg.add("GeoJSON")
# Running Pkg.update() will always give you the freshest version of GeoJSON
# Double-check that it works:
Pkg.test("GeoJSON")Basic Usage
Although we introduce types for representing GeoJSON objects, it works in tandem with the JSON.jl package, for parsing and printing objects. Here are some examples of its functionality:
- Parses a JSON String or IO stream into a GeoJSON object
julia> using GeoJSON
julia> osm_buildings = """{
"type": "FeatureCollection",
"features": [{
"type": "Feature",
"geometry": {
"type": "Polygon",
"coordinates": [
[
[13.42634, 52.49533],
[13.42660, 52.49524],
[13.42619, 52.49483],
[13.42583, 52.49495],
[13.42590, 52.49501],
[13.42611, 52.49494],
[13.42640, 52.49525],
[13.42630, 52.49529],
[13.42634, 52.49533]
]
]
},
"properties": {
"color": "rgb(255,200,150)",
"height": 150
}
}]
}"""
julia> buildings = GeoJSON.parse(osm_buildings) # GeoJSON.parse -- string or stream to AbstractGeoJSON types
FeatureCollection([Feature(Polygon({{{13.42634,52.49533},{13.4266,52.49524},{13.42619,52.49483},{13.42583,52.49495},{13.4259,52.49501},{13.42611,52.49494},{13.4264,52.49525},{13.4263,52.49529},{13.42634,52.49533}}},#undef,#undef),["height"=>150,"color"=>"rgb(255,200,150)"],#undef,#undef,#undef)],#undef,#undef)- Transforms a GeoJSON object into a nested Array or Dict
julia> GeoJSON.geojson2dict(buildings) # geojson2dict -- AbstractGeoJSON to Dict/Array-representation
Dict{String,Any} with 2 entries:
"features" => [["geometry"=>["coordinates"=>{{{13.42634,52.49533},{13.4266,52.49524},{13.42619,52.49483},{13.42583,52.49495},{13.4259,52.49…
"type" => "FeatureCollection"
julia> JSON.parse(osm_buildings) # should be comparable (if not the same)
Dict{String,Any} with 2 entries:
"features" => {["geometry"=>["coordinates"=>{{{13.42634,52.49533},{13.4266,52.49524},{13.42619,52.49483},{13.42583,52.49495},{13.4259,52.49…
"type" => "FeatureCollection"- Transforms from a nested Array/Dict to a GeoJSON object
julia> GeoJSON.dict2geojson(GeoJSON.geojson2dict(buildings))
FeatureCollection([Feature(Polygon({{{13.42634,52.49533},{13.4266,52.49524},{13.42619,52.49483},{13.42583,52.49495},{13.4259,52.49501},{13.42611,52.49494},{13.4264,52.49525},{13.4263,52.49529},{13.42634,52.49533}}},#undef,#undef),["height"=>150,"color"=>"rgb(255,200,150)"],#undef,#undef,#undef)],#undef,#undef)
julia> GeoJSON.parse(osm_buildings) # the original object (for comparison)
FeatureCollection([Feature(Polygon({{{13.42634,52.49533},{13.4266,52.49524},{13.42619,52.49483},{13.42583,52.49495},{13.4259,52.49501},{13.42611,52.49494},{13.4264,52.49525},{13.4263,52.49529},{13.42634,52.49533}}},#undef,#undef),["height"=>150,"color"=>"rgb(255,200,150)"],#undef,#undef,#undef)],#undef,#undef)- Returns a compact JSON representation as a String
julia> geojson(buildings) # AbstractGeoJSON to a string
"{\"features\":[{\"geometry\":{\"coordinates\":[[[13.42634,52.49533],[13.4266,52.49524],[13.42619,52.49483],[13.42583,52.49495],[13.4259,52.49501],[13.42611,52.49494],[13.4264,52.49525],[13.4263,52.49529],[13.42634,52.49533]]],\"type\":\"Polygon\"},\"properties\":{\"height\":150,\"color\":\"rgb(255,200,150)\"},\"type\":\"Feature\"}],\"type\":\"FeatureCollection\"}"
julia> JSON.json(JSON.parse(osm_buildings)) # compared with the JSON parser
"{\"features\":[{\"geometry\":{\"coordinates\":[[[13.42634,52.49533],[13.4266,52.49524],[13.42619,52.49483],[13.42583,52.49495],[13.4259,52.49501],[13.42611,52.49494],[13.4264,52.49525],[13.4263,52.49529],[13.42634,52.49533]]],\"type\":\"Polygon\"},\"properties\":{\"height\":150,\"color\":\"rgb(255,200,150)\"},\"type\":\"Feature\"}],\"type\":\"FeatureCollection\"}"- Writes a compact (no extra whitespace or identation) JSON representation to the supplied IO.
GeoJSON.print(io::IO, obj::AbstractGeoJSON)GeoJSON Objects
This library implements the following GeoJSON Objects described in The GeoJSON Format Specification.
CRSPosition-
Geometry <: AbstractGeoJSONPoint <: GeometryMultiPoint <: GeometryLineString <: GeometryMultiLineString <: GeometryPolygon <: GeometryMultiPolygon <: GeometryGeometryCollection <: Geometry
Feature <: AbstractGeoJSONFeatureCollection <: AbstractGeoJSON
The following methods are implemented for all AbstractGeoJSON objects:
hasbbox(obj::AbstractGeoJSON) # returns true if obj has a "bbox" key
hascrs(obj::AbstractGeoJSON) # returns true if obj has a "crs" key
bbox(obj::AbstractGeoJSON) # returns the boundingbox of obj
crs(obj::AbstractGeoJSON) # returns the coordinate reference systemIn addition, the Feature object also implements hasid(obj::Feature).
GeoJSON Attributes (GEO_Interface)
In accordance with the GeoJSON format (and the geo_interface), the following methods are implemented for each of the GeoJSON objects:
# GeoJSON (methods,)
# --------------------------------------------
((MultiPolygon, (coordinates,)),
(Polygon, (coordinates,)),
(MultiLineString, (coordinates,)),
(LineString, (coordinates,)),
(MultiPoint, (coordinates,)),
(Point, (coordinates,)),
(GeometryCollection, (geometries,)),
(Feature, (geometry, properties, id)),
(FeatureCollection, (features,)))
