example from Lynn Root's workshop.

pyladies_practice_geojson

import geojson

import parse as p     #shorter name for our parse program

def create_map(data_file):
        """csv file -> parse -> creates a geojson - javascript object notation - file """

        # define the type of geoJSON that we're creating
        geo_map = {"type": "FeatureCollection"}  #GeoJSON specification

        # define an empty list to collect each latitude and longitude point
        item_list = []

        # iterate over our data to create the geoJSON document (list of points_)
        # index is row number, line is row
        # using built-in function enumerate gives us those (index, line) for each row

        for index, line in enumerate(data_file):
                if line['X'] == "0" or line ['Y'] == "0":
                        continue  #skip those blank values because it will think they're the equator

                data = {}
                data['type'] = 'Feature'    #this is a geoJSON thing
                data['id'] = index                      #row number
                data['properties'] = {'title': line['Category'], 'description':line['Descript'],
                                                        'data':line['Date'], 'location':line['Location']}
                data['geometry'] = {'type': 'Point', 'coordinates': (line["X"], line["Y"])}    #geoJSON option for plotting
                item_list.append(data)

        #note that value of the properties key is another dict
        #same for geometry
        #coordinates are set to a tuple

        # iterate over each point and add it to the geoJSON object
        for point in item_list:
                geo_map.setdefault('features', []).append(point)

        #setdefault gives features all the points in the form of filling that empty list

        # write to a new GeoJSON file
        with open("file_sf.geojson", "w") as f:
                f.write(geojson.dumps(geo_map))

        #with will automatically close the file for you when it's done
        #w is for writing to a new file, wb is for appending to an existing file

def main():
        data = p.parse(p.MY_FILE, ",")

        return create_map(data)

if __name__== "__main__":
        main()