colouring-montreal/etl/get_test_polygons.py

"""Download and load a small open dataset for testing

Run this to create a CSV of buildings geometries.

Then run:
- load_geometries.sh (loading geometries to the database)
- create_buildings.sh (creating empty building records for each geometry)
"""
# -*- coding: utf-8 -*-
import os
import subprocess

import osmnx

# configure logging/caching
osmnx.config(log_console=True, use_cache=True)

# configure the image display
size = 256

# load buildings from about 1.5km² around UCL
point = (51.524498, -0.133874)
dist = 612
tags = {"building": True}
gdf = osmnx.features_from_point(point, tags, dist=dist)

# preview image
gdf_proj = osmnx.projection.project_gdf(gdf, to_crs={"init": "epsg:3857"})
gdf_proj = gdf_proj[gdf_proj.geometry.type == "Polygon"]

fig, ax = osmnx.plot_footprints(
    gdf_proj,
    bgcolor="#333333",
    color="w",
    figsize=(4, 4),
    save=True,
    show=False,
    close=True,
    filepath="test_buildings_preview.png",
    dpi=600,
)

# save
test_dir = os.path.dirname(__file__)
test_data_geojson = str(os.path.join(test_dir, "test_buildings.geojson"))
subprocess.run(["rm", test_data_geojson])
gdf_to_save = gdf_proj.reset_index()[["osmid", "geometry"]]

gdf_to_save.rename(columns={"osmid": "fid"}).to_file(
    test_data_geojson, driver="GeoJSON"
)

# convert to CSV
test_data_csv = str(os.path.join(test_dir, "test_buildings.3857.csv"))
subprocess.run(["rm", test_data_csv])
subprocess.run(
    [
        "ogr2ogr",
        "-f",
        "CSV",
        test_data_csv,
        test_data_geojson,
        "-lco",
        "GEOMETRY=AS_WKT",
    ]
)

# add SRID for ease of loading to PostgreSQL
subprocess.run(["sed", "-i", 's/^"POLYGON/"SRID=3857;POLYGON/', test_data_csv])