[GitHub] [sedona] jiayuasu commented on issue #814: Convert Featurecollection to SpatialRDD

["jiayuasu (via GitHub)" <gi...@apache.org>]

jiayuasu commented on issue #814:
URL: https://github.com/apache/sedona/issues/814#issuecomment-1495452309

   @conect 
   
   Test data:
   
   ```
   { "type": "FeatureCollection",
       "features": [
         { "type": "Feature",
           "geometry": {"type": "Point", "coordinates": [102.0, 0.5]},
           "properties": {"prop0": "value0"}
           },
         { "type": "Feature",
           "geometry": {
             "type": "LineString",
             "coordinates": [
               [102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [105.0, 1.0]
               ]
             },
           "properties": {
             "prop0": "value1",
             "prop1": 0.0
             }
           },
         { "type": "Feature",
            "geometry": {
              "type": "Polygon",
              "coordinates": [
                [ [100.0, 0.0], [101.0, 0.0], [101.0, 1.0],
                  [100.0, 1.0], [100.0, 0.0] ]
                ]
            },
            "properties": {
              "prop0": "value2",
              "prop1": {"this": "that"}
              }
            }
          ]
        }
   ```
   
   Code:
   
   ```scala
         val schema = "type string, features array<struct<type string, geometry string, properties map<string, string>>>"
         val df = sparkSession.read.schema(schema).option("multiLine", "true").json(geojsonFeatureCollection)
         val parsedDf = df.selectExpr("explode(features) as features").select("features.*")
           .withColumn("geometry", expr("ST_GeomFromGeoJSON(geometry)"))
           .withColumn("prop0", expr("properties['prop0']")).drop("properties").drop("type")
         parsedDf.show()
         parsedDf.printSchema()
   ```
   
   Output
   
   ```
   +--------------------+------+
   |            geometry| prop0|
   +--------------------+------+
   |     POINT (102 0.5)|value0|
   |LINESTRING (102 0...|value1|
   |POLYGON ((100 0, ...|value2|
   +--------------------+------+
   
   root
    |-- geometry: geometry (nullable = false)
    |-- prop0: string (nullable = true)
   
   
   ```
   
   To SpatialRDD and saveAsGeoJSON again
   
   ```
         var spatialRDD = Adapter.toSpatialRdd(parsedDf, "geometry")
         spatialRDD.saveAsGeoJSON("testOutput.json")
   ```
   
   testOutput.json content
   ```
   {"type":"Feature","geometry":{"type":"Point","coordinates":[102.0,0.5]},"properties":{"prop0":"value0"}}
   {"type":"Feature","geometry":{"type":"LineString","coordinates":[[102.0,0.0],[103.0,1.0],[104.0,0.0],[105.0,1.0]]},"properties":{"prop0":"value1"}}
   {"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[100.0,0.0],[101.0,0.0],[101.0,1.0],[100.0,1.0],[100.0,0.0]]]},"properties":{"prop0":"value2"}}
   ```
   
   This works for Scala, Java, Python, R. The detailed explanation can be found here: https://sedona.apache.org/1.4.0/tutorial/sql/#load-geojson-using-spark-json-data-source


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