provide extra converters

for interoperability with DataFrames
JuliaGeo · Mar 8, 2015 · 1ac8086 · 1ac8086
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diff --git a/README.md b/README.md
@@ -87,6 +87,33 @@ 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\"}"
 ```
 
+- Convert a GeoJSON.FeatureCollection to a DataFrame
+
+```julia
+julia> GeoJSON.geojson2df(obj)
+4x4 DataFrame
+| Row | id |
+|-----|----|
+| 1   | NA |
+| 2   | NA |
+| 3   | NA |
+| 4   | NA |
+
+| Row | geometry                                                                                                                                                                                                                                                                                  |
+|-----|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 1   | Polygon([[[13.4263,52.4953],[13.4266,52.4952],[13.4262,52.4948],[13.4258,52.495],[13.4259,52.495],[13.4261,52.4949],[13.4264,52.4952],[13.4263,52.4953],[13.4263,52.4953]]],#undef,#undef)                                                                                                |
+| 2   | Polygon([[[13.4271,52.4954],[13.4275,52.4952],[13.4275,52.4952],[13.4274,52.4952],[13.4272,52.4952],[13.4269,52.495],[13.4271,52.4949],[13.4269,52.4947],[13.4265,52.4948],[13.4266,52.4949],[13.4268,52.4948],[13.4269,52.495],[13.4268,52.495],[13.4271,52.4954]]],#undef,#undef)       |
+| 3   | MultiPolygon([[[[13.4275,52.4944],[13.4279,52.4949],[13.428,52.4949],[13.4276,52.4944],[13.428,52.4943],[13.4285,52.4948],[13.4285,52.4948],[13.428,52.4942],[13.4275,52.4944]]],[[[13.428,52.495],[13.428,52.4949],[13.4284,52.4948],[13.4285,52.4948],[13.428,52.495]]]],#undef,#undef) |
+| 4   | Polygon([[[13.4286,52.4948],[13.4292,52.4947],[13.4287,52.4941],[13.4285,52.4942],[13.429,52.4947],[13.4288,52.4947],[13.4284,52.4942],[13.4282,52.4943],[13.4286,52.4947],[13.4285,52.4948],[13.4286,52.4948]]],#undef,#undef)                                                           |
+
+| Row | color              | height |
+|-----|--------------------|--------|
+| 1   | "rgb(255,200,150)" | 150    |
+| 2   | "rgb(180,240,180)" | 130    |
+| 3   | "rgb(200,200,250)" | 120    |
+| 4   | "rgb(150,180,210)" | 140    |
+```
+
 - Writes a compact (no extra whitespace or identation) JSON representation to the supplied IO.
 
 ```julia

diff --git a/REQUIRE b/REQUIRE
@@ -1,3 +1,4 @@
 julia 0.3
 JSON
+DataFrames
 Compat
diff --git a/src/GeoJSON.jl b/src/GeoJSON.jl
@@ -1,6 +1,6 @@
 module GeoJSON
 
-    using JSON, Compat
+    using JSON, DataFrames, Compat
 
     export
         Point,

diff --git a/src/parser.jl b/src/parser.jl
@@ -67,10 +67,47 @@ end
 
 geojson2dict(obj::Nothing) = obj
 
+function propertynames(obj::FeatureCollection)
+    columns = Set()
+    for feature in obj.features
+        if isdefined(feature, :properties)
+            for key in keys(feature.properties)
+                if in(key, columns)
+                    continue
+                end
+                push!(columns, key)
+            end
+        end
+    end
+    [["id","geometry"],sort(collect(columns))]
+end
+
+function geojson2df(obj::FeatureCollection)
+    nrows = length(obj.features)
+    if nrows == 0
+        return DataFrame()
+    end
+    colnames = propertynames(obj)
+    ncols = length(colnames)
+    df = DataFrame([[Any, Geometry], repeat([Any], inner = [ncols-2])],
+                   convert(Vector{Symbol}, colnames), nrows)
+    for i in 1:nrows
+        df[i, 1] = hasid(obj.features[i]) ? obj.features[i].id : NA
+        df[i, 2] = obj.features[i].geometry
+        if isdefined(obj.features[i], :properties)
+            for j in 3:ncols
+                df[i, j] = get(obj.features[i].properties, colnames[j], NA)
+            end
+        end
+    end
+    df
+end
+
 # String/File -> GeoJSON
 parse(input; kwargs...) = dict2geojson(JSON.parse(input; kwargs...))
 parsefile(filename; kwargs...) = dict2geojson(JSON.parsefile(filename; kwargs...))
 
 # GeoJSON -> String/IO
 geojson(obj::AbstractGeoJSON) = JSON.json(geojson2dict(obj))
+geojson{T <: AbstractGeoJSON}(obj::Vector{T}) = JSON.json(map(geojson2dict, obj))
 print(io::IO, obj::AbstractGeoJSON) = JSON.print(io, geojson2dict(obj))
diff --git a/test/runtests.jl b/test/runtests.jl
@@ -305,6 +305,13 @@ dict = GeoJSON.geojson2dict(feature)
 @fact dict["id"] => "a7xlmuwyjioy"
 @fact dict["type"] => "Feature"
 
+df = GeoJSON.geojson2df(testobj)
+@fact size(df) => (1,4)
+@fact df[1,:STATE_ABBR] => "ZZ"
+@fact df[1,:STATE_NAME] => "Top"
+@fact typeof(df[1,:geometry]) => GeometryCollection
+
+
 buildings = GeoJSON.parse(osm_buildings)
 @fact typeof(buildings) => FeatureCollection
 @fact GeoJSON.hasbbox(buildings) => false
@@ -323,12 +330,24 @@ feature = buildings.features[1]
 @fact GeoJSON.hasbbox(feature) => false
 @fact GeoJSON.hascrs(feature) => false
 
+df = GeoJSON.geojson2df(buildings)
+@fact size(df) => (4,4)
+@fact df[:height] => [150,130,120,140]
+@fact map(typeof, df[:geometry]) => [Polygon, Polygon, MultiPolygon, Polygon]
+@fact df[:color] => ["rgb(255,200,150)",
+                     "rgb(180,240,180)",
+                     "rgb(200,200,250)",
+                     "rgb(150,180,210)"]
+@fact all(DataFrames.isna(df[:id])) => true
+
 building_dict = GeoJSON.geojson2dict(buildings)
 @fact typeof(building_dict) => Dict{String,Any}
 @fact string(GeoJSON.parse(osm_buildings)) => string(GeoJSON.dict2geojson(building_dict))
 
 @fact GeoJSON.geojson(buildings) =>
 """{\"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\"},{\"geometry\":{\"coordinates\":[[[13.42706,52.49535],[13.42745,52.4952],[13.42745,52.4952],[13.42741,52.49516],[13.42717,52.49525],[13.42692,52.49501],[13.42714,52.49494],[13.42686,52.49466],[13.4265,52.49478],[13.42657,52.49486],[13.42678,52.4948],[13.42694,52.49496],[13.42675,52.49503],[13.42706,52.49535]]],\"type\":\"Polygon\"},\"properties\":{\"height\":130,\"color\":\"rgb(180,240,180)\"},\"type\":\"Feature\"},{\"geometry\":{\"coordinates\":[[[[13.42746,52.4944],[13.42794,52.49494],[13.42799,52.49492],[13.42755,52.49442],[13.42798,52.49428],[13.42846,52.4948],[13.42851,52.49478],[13.428,52.49422],[13.42746,52.4944]]],[[[13.42803,52.49497],[13.428,52.49493],[13.42844,52.49479],[13.42847,52.49483],[13.42803,52.49497]]]],\"type\":\"MultiPolygon\"},\"properties\":{\"height\":120,\"color\":\"rgb(200,200,250)\"},\"type\":\"Feature\"},{\"geometry\":{\"coordinates\":[[[13.42857,52.4948],[13.42918,52.49465],[13.42867,52.49412],[13.4285,52.49419],[13.42896,52.49465],[13.42882,52.49469],[13.42837,52.49423],[13.42821,52.49428],[13.42863,52.49473],[13.42853,52.49476],[13.42857,52.4948]]],\"type\":\"Polygon\"},\"properties\":{\"height\":140,\"color\":\"rgb(150,180,210)\"},\"type\":\"Feature\"}],\"type\":\"FeatureCollection\"}"""
+@fact GeoJSON.geojson(buildings.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\"},\"type\":\"Feature\"},{\"geometry\":{\"coordinates\":[[[13.42706,52.49535],[13.42745,52.4952],[13.42745,52.4952],[13.42741,52.49516],[13.42717,52.49525],[13.42692,52.49501],[13.42714,52.49494],[13.42686,52.49466],[13.4265,52.49478],[13.42657,52.49486],[13.42678,52.4948],[13.42694,52.49496],[13.42675,52.49503],[13.42706,52.49535]]],\"type\":\"Polygon\"},\"type\":\"Feature\"},{\"geometry\":{\"coordinates\":[[[[13.42746,52.4944],[13.42794,52.49494],[13.42799,52.49492],[13.42755,52.49442],[13.42798,52.49428],[13.42846,52.4948],[13.42851,52.49478],[13.428,52.49422],[13.42746,52.4944]]],[[[13.42803,52.49497],[13.428,52.49493],[13.42844,52.49479],[13.42847,52.49483],[13.42803,52.49497]]]],\"type\":\"MultiPolygon\"},\"type\":\"Feature\"},{\"geometry\":{\"coordinates\":[[[13.42857,52.4948],[13.42918,52.49465],[13.42867,52.49412],[13.4285,52.49419],[13.42896,52.49465],[13.42882,52.49469],[13.42837,52.49423],[13.42821,52.49428],[13.42863,52.49473],[13.42853,52.49476],[13.42857,52.4948]]],\"type\":\"Polygon\"},\"type\":\"Feature\"}]"""
 
 @fact GeoJSON.geojson(buildings) => JSON.json(JSON.parse(osm_buildings))
 @fact building_dict => JSON.parse(osm_buildings)
@@ -347,3 +366,5 @@ feature = obj.features[1]
 @fact length(feature.geometry.coordinates) => 1
 @fact length(feature.geometry.coordinates[1]) => 38
 @fact feature.geometry.coordinates[1][1] => feature.geometry.coordinates[1][end]
+
+