colouring-montreal/etl/get_test_polygons.py
2020-06-18 10:31:34 +01:00

57 lines
1.6 KiB
Python

"""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
gdf = osmnx.footprints_from_point(point=point, dist=dist)
# preview image
gdf_proj = osmnx.projection.project_gdf(gdf, to_crs={'init': 'epsg:3857'})
gdf_proj = gdf_proj[gdf_proj.geometry.apply(lambda g: g.geom_type != 'MultiPolygon')]
fig, ax = osmnx.plot_footprints(gdf_proj, bgcolor='#333333', color='w', figsize=(4,4),
save=True, show=False, close=True,
filename='test_buildings_preview', 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(
)[
['index', 'geometry']
]
gdf_to_save.rename(
columns={'index': '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])