geo-l1-tokyo-busstop-buffer
Map (reference ← swipe → agent)
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I'm refreshing the 400 m walkable-catchment layer for `tokyo_connectors.geojson` so I can join the result to our ridership table. Can you draw a 400 m buffer around every connector and save the result as `tokyo_stop_catchments.geoparquet` in GeoParquet, with one Polygon or MultiPolygon row per input connector? Please keep `connector_id` on every row with the original value preserved, since that's the join key.
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System info
{
"adapter": "openrouter",
"model": "google/gemma-4-26b-a4b-it",
"base_url": "https://openrouter.ai/api/v1"
}
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Bash
ls -F
tokyo_connectors.geojson
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Bash
head -n 20 tokyo_connectors.geojson
{
"type": "FeatureCollection",
"name": "tokyo_connectors",
"crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:OGC:1.3:CRS84" } },
"features": [
{ "type": "Feature", "properties": { "connector_id": "0096dba5-f5b5-4cd6-b10b-de96fac11d0c" }, "geometry": { "type": "Point", "coordinates": [ 139.7666758, 35.6816829 ] } },
{ "type": "Feature", "properties": { "connector_id": "00bfefa0-b287-48ac-acb4-9ee43e8ccc3e" }, "geometry": { "type": "Point", "coordinates": [ 139.767766599999987, 35.6817796 ] } },
{ "type": "Feature", "properties": { "connector_id": "00c74771-e2be-486d-8962-a411c4bdc882" }, "geometry": { "type": "Point", "coordinates": [ 139.766474100000011, 35.6817342 ] } },
{ "type": "Feature", "properties": { "connector_id": "012ea04f-85ec-417a-a7c4-c982b3de4436" }, "geometry": { "type": "Point", "coordinates": [ 139.766754, 35.6814118 ] } },
{ "type": "Feature", "properties": { "connector_id": "0365ffb5-6290-4cc7-899c-946d30e997bd" }, "geometry": { "type": "Point", "coordinates": [ 139.767668500000013, 35.6812699 ] } },
{ "type": "Feature", "properties": { "connector_id": "03aed995-97ff-4082-9ea4-461476e6fb59" }, "geometry": { "type": "Point", "coordinates": [ 139.766743, 35.6816612 ] } },
{ "type": "Feature", "properties": { "connector_id": "03bf62b2-8ef2-478b-ad8d-ee2d34dcb355" }, "geometry": { "type": "Point", "coordinates": [ 139.7680073, 35.68172 ] } },
{ "type": "Feature", "properties": { "connector_id": "041abf7f-8f32-431b-996d-36e9aaba89a7" }, "geometry": { "type": "Point", "coordinates": [ 139.7663958, 35.6814469 ] } },
{ "type": "Feature", "properties": { "connector_id": "0523ae99-9fed-4137-8345-2f8a155ed2b6" }, "geometry": { "type": "Point", "coordinates": [ 139.7662568, 35.68123940000001 ] } },
{ "type": "Feature", "properties": { "connector_id": "08b9b8e7-12fc-46b4-bd3a-7e94ee1d280b" }, "geometry": { "type": "Point", "coordinates": [ 139.7668761, 35.681728 ] } },
{ "type": "Feature", "properties": { "connector_id": "08cdb272-cd07-4501-b5b7-f41cf8ae0b24" }, "geometry": { "type": "Point", "coordinates": [ 139.7672097, 35.6826518 ] } },
{ "type": "Feature", "properties": { "connector_id": "0bfdf570-a7c6-44f8-9d7b-31203791523f" }, "geometry": { "type": "Point", "coordinates": [ 139.766253299999988, 35.6811865 ] } },
{ "type": "Feature", "properties": { "connector_id": "0dc5371d-3b64-4a73-90d7-e848a695a1f5" }, "geometry": { "type": "Point", "coordinates": [ 139.767078199999986, 35.6815685 ] } },
{ "type": "Feature", "properties": { "connector_id": "0eb0b1c6-28be-4dcd-aa29-9d2df97bdbaa" }, "geometry": { "type": "Point", "coordinates": [ 139.7665611, 35.6827282 ] } },
{ "type": "Feature", "properties": { "connector_id": "0ff6361e-d6db-4218-b7d0-c0c3a6213b67" }, "geometry": { "type": "Point", "coordinates": [ 139.7662075, 35.6826326 ] } },
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Write
solve.py
content · 47 lines · py
import geopandas as gpd
def main():
input_file = "tokyo_connectors.geojson"
output_file = "tokyo_stop_catchments.geoparquet"
buffer_dist = 400 # meters
print(f"Reading {input_file}...")
gdf = gpd.read_file(input_file)
# Check CRS. GeoJSON is usually WGS84 (EPSG:4326)
if gdf.crs is None:
print("No CRS found, assuming EPSG:4326")
gdf.set_crs(epsg=4326, inplace=True)
# Project to a local metric CRS for accurate buffering.
# For Tokyo, EPSG:6677 (JGD2011 / Japan Plane Rectangular CS IX) or EPSG:3857.
# EPSG:6677 is highly accurate for Tokyo.
# Let's use EPSG:6677.
print("Projecting to EPSG:6677 for buffering...")
gdf_projected = gdf.to_crs(epsg=6677)
print(f"Creating {buffer_dist}m buffers...")
# Create buffer. gdf.geometry.buffer returns a Series of geometries.
# We want to keep the connector_id.
gdf_projected['geometry'] = gdf_projected.buffer(buffer_dist)
# Convert back to WGS84 for the final output?
# Usually, it's better to keep it in a metric CRS if it's for spatial analysis,
# but GeoParquet can handle both. However, the prompt doesn't specify.
# Let's reproject back to 4326 as it's standard for most web/GIS apps
# unless specified otherwise.
print("Reprojecting back to EPSG:4326...")
gdf_final = gdf_projected.to_crs(epsg=4326)
# Ensure connector_id is preserved.
# When we did gdf_projected['geometry'] = ..., we kept the index and other columns.
# We should check if connector_id is still there.
print(f"Columns in result: {gdf_final.columns.tolist()}")
print(f"Saving to {output_file}...")
gdf_final.to_parquet(output_file)
print("Done!")
if __name__ == "__main__":
main()
Wrote solve.py (1765 chars).
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Bash
python solve.py
Reading tokyo_connectors.geojson... Projecting to EPSG:6677 for buffering... Creating 400m buffers... Reprojecting back to EPSG:4326... Columns in result: ['connector_id', 'geometry'] Saving to tokyo_stop_catchments.geoparquet... Done!
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Bash
python -c "import geopandas as gpd; gdf = gpd.read_parquet('tokyo_stop_catchment...
connector_id geometry
0 0096dba5-f5b5-4cd6-b10b-de96fac11d0c POLYGON ((139.77109 35.68169, 139.77107 35.681...
1 00bfefa0-b287-48ac-acb4-9ee43e8ccc3e POLYGON ((139.77219 35.68178, 139.77216 35.681...
2 00c74771-e2be-486d-8962-a411c4bdc882 POLYGON ((139.77089 35.68174, 139.77087 35.681...
3 012ea04f-85ec-417a-a7c4-c982b3de4436 POLYGON ((139.77117 35.68141, 139.77115 35.681...
4 0365ffb5-6290-4cc7-899c-946d30e997bd POLYGON ((139.77209 35.68127, 139.77207 35.680...
{"$schema": "https://proj.org/schemas/v0.7/projjson.schema.json", "type": "GeographicCRS", "name": "WGS 84", "datum_ensemble": {"name": "World Geodetic System 1984 ensemble", "members": [{"name": "World Geodetic System 1984 (Transit)"}, {"name": "World Geodetic System 1984 (G730)"}, {"name": "World Geodetic System 1984 (G873)"}, {"name": "World Geodetic System 1984 (G1150)"}, {"name": "World Geodetic System 1984 (G1674)"}, {"name": "World Geodetic System 1984 (G1762)"}, {"name": "World Geodetic System 1984 (G2139)"}, {"name": "World Geodetic System 1984 (G2296)"}], "ellipsoid": {"name": "WGS 84", "semi_major_axis": 6378137, "inverse_flattening": 298.257223563}, "accuracy": "2.0", "id": {"authority": "EPSG", "code": 6326}}, "coordinate_system": {"subtype": "ellipsoidal", "axis": [{"name": "Geodetic latitude", "abbreviation": "Lat", "direction": "north", "unit": "degree"}, {"name": "Geodetic longitude", "abbreviation": "Lon", "direction": "east", "unit": "degree"}]}, "scope": "Horizontal component of 3D system.", "area": "World.", "bbox": {"south_latitude": -90, "west_longitude": -180, "north_latitude": 90, "east_longitude": 180}, "id": {"authority": "EPSG", "code": 4326}}
Polygon 300
Name: count, dtype: int64
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