wkyle/shp2geojson

Python script for converting ESRI shapefiles to geojson for the web

shp2geojson

Python script for converting ESRI shapefiles to geojson for the web

Introduction

A FeatureCollection in GeoJSON looks like this:

{ "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": "value0",
          "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": "value0",
           "prop1": {"this": "that"}
           }
         }
       ]
     }

It's made up of features which can be polygons, lines, points, multipart polygons, etc.

Converting

Popular interactive mapping tools for the web seem to prefer geojson files (.json, .geojson) for their maps but the Canadian government only supplies ESRI shapefiles (.shp) of Federal Electoral Districts and other products.

Using the python3 module pyshp we can read shapefiles and adjust the syntax to build a geojson file using the python3 module geojson.

Some Options

• Read shapefiles, see the feature fields (properties) and select which properties to include in the final geojson
• Select the numerical precision with which to output the geojson to optimize file size
• Optionally split multipart polygons into separate polygons

Current Hangups

It's possible that multipart polygons contain holes. How to determine if this is the case and what to do with it is something to be figured out.