geo-l1-cairo-multipoint-hull
Map (reference ← swipe → agent)
0:00
I'm putting together the accessibility report for the Metro, and its static maps need to show how far each station's underground box reaches at street level. `cairo_metro_stations.geojson` has each station's street-level entrances. Can you compute the convex hull of each station's entrances and save the result to `cairo_metro_hulls.geojson`, one Polygon per station? Every row must carry `station_name_en` and `station_name_ar`, both non-empty, with the original Arabic strings and diacritics preserved exactly as they appear in the input.
0:00
System info
{
"adapter": "openrouter",
"model": "deepseek/deepseek-v4-flash",
"base_url": "https://openrouter.ai/api/v1"
}
0:13
Let me start by reading the input file to understand its structure.
0:13
Read
/work/cairo_metro_stations.geojson
1 {
2 "type": "FeatureCollection",
3 "name": "cairo_metro_stations",
4 "crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:OGC:1.3:CRS84" } },
5 "features": [
6 { "type": "Feature", "properties": { "station_name_en": "Al-Shohadaa", "station_name_ar": "الشهداء" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.246441, 30.063109 ], [ 31.246778, 30.062428 ], [ 31.246859, 30.063158 ], [ 31.247736, 30.061538 ], [ 31.247931, 30.062636 ] ] } },
7 { "type": "Feature", "properties": { "station_name_en": "Attaba", "station_name_ar": "العتبة" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.246196, 30.051508 ], [ 31.246396, 30.051849 ], [ 31.246716, 30.051944 ], [ 31.246936, 30.052384 ], [ 31.247559, 30.052018 ] ] } },
8 { "type": "Feature", "properties": { "station_name_en": "Cairo University", "station_name_ar": "جامعة القاهرة" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.200216, 30.025256 ], [ 31.200826, 30.026512 ], [ 31.201257, 30.02592 ], [ 31.201463, 30.025147 ], [ 31.20167, 30.026648 ] ] } },
9 { "type": "Feature", "properties": { "station_name_en": "Dokki", "station_name_ar": "الدقي" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.211926, 30.038446 ], [ 31.212858, 30.038563 ], [ 31.213071, 30.039014 ], [ 31.213408, 30.037575 ] ] } },
10 { "type": "Feature", "properties": { "station_name_en": "El Demerdash", "station_name_ar": "الدمرداش" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.272726, 30.079096 ], [ 31.272841, 30.079167 ], [ 31.273817, 30.078925 ], [ 31.274032, 30.079479 ] ] } },
11 { "type": "Feature", "properties": { "station_name_en": "El Malek El Saleh", "station_name_ar": "الملك الصالح" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.233442, 30.019095 ], [ 31.233473, 30.018682 ], [ 31.234504, 30.017367 ], [ 31.234545, 30.017379 ] ] } },
12 { "type": "Feature", "properties": { "station_name_en": "El-Marg", "station_name_ar": "المرج" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.334217, 30.146468 ], [ 31.334253, 30.146538 ], [ 31.334782, 30.146493 ] ] } },
13 { "type": "Feature", "properties": { "station_name_en": "Ghamra", "station_name_ar": "غمرة" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.263164, 30.068985 ], [ 31.263197, 30.068259 ], [ 31.264394, 30.068864 ] ] } },
14 { "type": "Feature", "properties": { "station_name_en": "Hadayek El-Zaitoun", "station_name_ar": "حدائق الزيتون" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.3063, 30.122913 ], [ 31.30776, 30.123157 ], [ 31.307789, 30.122103 ], [ 31.307849, 30.12264 ] ] } },
15 { "type": "Feature", "properties": { "station_name_en": "Helmeyet El-Zaitoun", "station_name_ar": "حلمية الزيتون" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.302031, 30.11224 ], [ 31.302815, 30.111791 ], [ 31.303183, 30.111908 ] ] } },
16 { "type": "Feature", "properties": { "station_name_en": "Helwan", "station_name_ar": "حلوان" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.333401, 29.847533 ], [ 31.333518, 29.84856 ], [ 31.33383, 29.849118 ], [ 31.33423, 29.849025 ] ] } },
17 { "type": "Feature", "properties": { "station_name_en": "Maadi", "station_name_ar": "المعادي" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.256977, 29.960391 ], [ 31.256996, 29.961004 ], [ 31.25776, 29.95986 ], [ 31.25825, 29.959814 ], [ 31.258343, 29.961018 ] ] } },
18 { "type": "Feature", "properties": { "station_name_en": "Manshiet El-Sadr", "station_name_ar": "منشية الصدر" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.286919, 30.07915 ], [ 31.287036, 30.078534 ], [ 31.287853, 30.078947 ] ] } },
19 { "type": "Feature", "properties": { "station_name_en": "Mar Girgis", "station_name_ar": "مار جرجس" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.229596, 30.005582 ], [ 31.230357, 30.006424 ], [ 31.230863, 30.006943 ] ] } },
20 { "type": "Feature", "properties": { "station_name_en": "Mohamed Naguib", "station_name_ar": "محمد نجيب" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.245937, 30.043448 ], [ 31.246011, 30.042638 ], [ 31.246072, 30.042795 ], [ 31.246112, 30.043492 ] ] } },
21 { "type": "Feature", "properties": { "station_name_en": "Nasser", "station_name_ar": "عبد الناصر" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.243015, 30.052462 ], [ 31.243026, 30.053981 ], [ 31.244356, 30.052241 ], [ 31.244365, 30.053045 ] ] } },
22 { "type": "Feature", "properties": { "station_name_en": "Opera", "station_name_ar": "الأوبرا" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.223629, 30.042483 ], [ 31.22406, 30.041978 ], [ 31.224966, 30.042008 ] ] } },
23 { "type": "Feature", "properties": { "station_name_en": "Saad Zaghloul", "station_name_ar": "سعد زغلول" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.248006, 30.037688 ], [ 31.248884, 30.037798 ], [ 31.248954, 30.037359 ] ] } },
24 { "type": "Feature", "properties": { "station_name_en": "Sadat", "station_name_ar": "السادات" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.235032, 30.043948 ], [ 31.236163, 30.044623 ], [ 31.236249, 30.044071 ], [ 31.236357, 30.043795 ], [ 31.236493, 30.044874 ] ] } },
25 { "type": "Feature", "properties": { "station_name_en": "Sayeda Zeinab", "station_name_ar": "السيدة زينب" }, "geometry": { "type": "MultiPoint", "coordinates": [ [ 31.238434, 30.030095 ], [ 31.23933, 30.028708 ], [ 31.239612, 30.029943 ], [ 31.239711, 30.028807 ] ] } }
26 ]
27 }
0:21
Now I understand the data. I need to: 1. Read the GeoJSON file with its MultiPoint features 2. For each station, compute the convex hull of its entrance points (the MultiPoint coordinates) 3. Output a GeoJSON with Polygon features, each carrying `station_name_en` and `station_name_ar` Let me write a Python script using geopandas and shapely to do this.
0:21
Write
/work/solve.py
content · 46 lines · py
#!/usr/bin/env python3
"""
Read Cairo Metro station entrances (MultiPoint).
Compute the convex hull of each station's entrances.
Write one Polygon per station, preserving station_name_en and station_name_ar.
"""
import geopandas as gpd
from shapely.geometry import MultiPoint, Polygon
# 1. Read input
gdf = gpd.read_file("/work/cairo_metro_stations.geojson")
print(f"Read {len(gdf)} station features.")
# 2. Build convex hull per station
rows = []
for _, row in gdf.iterrows():
geom = row.geometry
if geom is None:
continue # skip if no geometry
hull = geom.convex_hull # shapely Geometry (Polygon or Point...)
# convex_hull of a MultiPoint that has only 1 or 2 distinct points
# can be Point or LineString. The task asks for Polygon.
# If hull is not a Polygon, buffer it trivially to make a tiny polygon.
if hull.geom_type == "Polygon":
out_geom = hull
else:
# For safety: buffer by a tiny amount to get a Polygon
out_geom = hull.buffer(1e-10, cap_style=3, join_style=2)
rows.append({
"station_name_en": row["station_name_en"],
"station_name_ar": row["station_name_ar"],
"geometry": out_geom,
})
out_gdf = gpd.GeoDataFrame(rows, crs=gdf.crs)
# 3. Validate non-empty strings
for _, r in out_gdf.iterrows():
if not r["station_name_en"] or not r["station_name_ar"]:
raise ValueError(f"Empty name found for station: {r}")
# 4. Write output
out_gdf.to_file("/work/cairo_metro_hulls.geojson", driver="GeoJSON")
print(f"Wrote {len(out_gdf)} hull features to /work/cairo_metro_hulls.geojson")Wrote /work/solve.py (1604 chars).
0:33
Let me run the script to generate the hulls.
0:33
Bash
cd /work && python solve.py
Read 20 station features. Wrote 20 hull features to /work/cairo_metro_hulls.geojson
0:49
Good, it ran successfully. Let me verify the output file now.
0:49
Read
/work/cairo_metro_hulls.geojson
1 {
2 "type": "FeatureCollection",
3 "name": "cairo_metro_hulls",
4 "crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:OGC:1.3:CRS84" } },
5 "features": [
6 { "type": "Feature", "properties": { "station_name_en": "Al-Shohadaa", "station_name_ar": "الشهداء" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.247736, 30.061538 ], [ 31.246778, 30.062428 ], [ 31.246441, 30.063109 ], [ 31.246859, 30.063158 ], [ 31.247931, 30.062636 ], [ 31.247736, 30.061538 ] ] ] } },
7 { "type": "Feature", "properties": { "station_name_en": "Attaba", "station_name_ar": "العتبة" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.246196, 30.051508 ], [ 31.246396, 30.051849 ], [ 31.246936, 30.052384 ], [ 31.247559, 30.052018 ], [ 31.246196, 30.051508 ] ] ] } },
8 { "type": "Feature", "properties": { "station_name_en": "Cairo University", "station_name_ar": "جامعة القاهرة" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.201463, 30.025147 ], [ 31.200216, 30.025256 ], [ 31.200826, 30.026512 ], [ 31.20167, 30.026648 ], [ 31.201463, 30.025147 ] ] ] } },
9 { "type": "Feature", "properties": { "station_name_en": "Dokki", "station_name_ar": "الدقي" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.213408, 30.037575 ], [ 31.211926, 30.038446 ], [ 31.213071, 30.039014 ], [ 31.213408, 30.037575 ] ] ] } },
10 { "type": "Feature", "properties": { "station_name_en": "El Demerdash", "station_name_ar": "الدمرداش" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.273817, 30.078925 ], [ 31.272726, 30.079096 ], [ 31.272841, 30.079167 ], [ 31.274032, 30.079479 ], [ 31.273817, 30.078925 ] ] ] } },
11 { "type": "Feature", "properties": { "station_name_en": "El Malek El Saleh", "station_name_ar": "الملك الصالح" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.234504, 30.017367 ], [ 31.233473, 30.018682 ], [ 31.233442, 30.019095 ], [ 31.234545, 30.017379 ], [ 31.234504, 30.017367 ] ] ] } },
12 { "type": "Feature", "properties": { "station_name_en": "El-Marg", "station_name_ar": "المرج" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.334217, 30.146468 ], [ 31.334253, 30.146538 ], [ 31.334782, 30.146493 ], [ 31.334217, 30.146468 ] ] ] } },
13 { "type": "Feature", "properties": { "station_name_en": "Ghamra", "station_name_ar": "غمرة" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.263197, 30.068259 ], [ 31.263164, 30.068985 ], [ 31.264394, 30.068864 ], [ 31.263197, 30.068259 ] ] ] } },
14 { "type": "Feature", "properties": { "station_name_en": "Hadayek El-Zaitoun", "station_name_ar": "حدائق الزيتون" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.307789, 30.122103 ], [ 31.3063, 30.122913 ], [ 31.30776, 30.123157 ], [ 31.307849, 30.12264 ], [ 31.307789, 30.122103 ] ] ] } },
15 { "type": "Feature", "properties": { "station_name_en": "Helmeyet El-Zaitoun", "station_name_ar": "حلمية الزيتون" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.302815, 30.111791 ], [ 31.302031, 30.11224 ], [ 31.303183, 30.111908 ], [ 31.302815, 30.111791 ] ] ] } },
16 { "type": "Feature", "properties": { "station_name_en": "Helwan", "station_name_ar": "حلوان" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.333401, 29.847533 ], [ 31.333518, 29.84856 ], [ 31.33383, 29.849118 ], [ 31.33423, 29.849025 ], [ 31.333401, 29.847533 ] ] ] } },
17 { "type": "Feature", "properties": { "station_name_en": "Maadi", "station_name_ar": "المعادي" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.25825, 29.959814 ], [ 31.25776, 29.95986 ], [ 31.256977, 29.960391 ], [ 31.256996, 29.961004 ], [ 31.258343, 29.961018 ], [ 31.25825, 29.959814 ] ] ] } },
18 { "type": "Feature", "properties": { "station_name_en": "Manshiet El-Sadr", "station_name_ar": "منشية الصدر" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.287036, 30.078534 ], [ 31.286919, 30.07915 ], [ 31.287853, 30.078947 ], [ 31.287036, 30.078534 ] ] ] } },
19 { "type": "Feature", "properties": { "station_name_en": "Mar Girgis", "station_name_ar": "مار جرجس" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.229596, 30.005582 ], [ 31.230357, 30.006424 ], [ 31.230863, 30.006943 ], [ 31.229596, 30.005582 ] ] ] } },
20 { "type": "Feature", "properties": { "station_name_en": "Mohamed Naguib", "station_name_ar": "محمد نجيب" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.246011, 30.042638 ], [ 31.245937, 30.043448 ], [ 31.246112, 30.043492 ], [ 31.246072, 30.042795 ], [ 31.246011, 30.042638 ] ] ] } },
21 { "type": "Feature", "properties": { "station_name_en": "Nasser", "station_name_ar": "عبد الناصر" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.244356, 30.052241 ], [ 31.243015, 30.052462 ], [ 31.243026, 30.053981 ], [ 31.244365, 30.053045 ], [ 31.244356, 30.052241 ] ] ] } },
22 { "type": "Feature", "properties": { "station_name_en": "Opera", "station_name_ar": "الأوبرا" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.22406, 30.041978 ], [ 31.223629, 30.042483 ], [ 31.224966, 30.042008 ], [ 31.22406, 30.041978 ] ] ] } },
23 { "type": "Feature", "properties": { "station_name_en": "Saad Zaghloul", "station_name_ar": "سعد زغلول" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.248954, 30.037359 ], [ 31.248006, 30.037688 ], [ 31.248884, 30.037798 ], [ 31.248954, 30.037359 ] ] ] } },
24 { "type": "Feature", "properties": { "station_name_en": "Sadat", "station_name_ar": "السادات" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.236357, 30.043795 ], [ 31.235032, 30.043948 ], [ 31.236493, 30.044874 ], [ 31.236357, 30.043795 ] ] ] } },
25 { "type": "Feature", "properties": { "station_name_en": "Sayeda Zeinab", "station_name_ar": "السيدة زينب" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 31.23933, 30.028708 ], [ 31.238434, 30.030095 ], [ 31.239612, 30.029943 ], [ 31.239711, 30.028807 ], [ 31.23933, 30.028708 ] ] ] } }
26 ]
27 }
1:06
Let me verify the output against the requirements: 1. ✅ File saved as `cairo_metro_hulls.geojson` in the working directory. 2. ✅ Each row is a Polygon (convex hull of the entrances). 3. ✅ Each row carries `station_name_en` and `station_name_ar`, both non-empty. 4. ✅ Arabic strings preserved with original diacritics — let me verify a few: - الشهداء ✓ - العتبة ✓ - جامعة القاهرة ✓ - الدقي ✓ - الدمرداش ✓ - الملك الصالح ✓ - المرج ✓ - غمرة ✓ - حدائق الزيتون ✓ - حلمية الزيتون ✓ - حلوان ✓ - المعادي ✓ - منشية الصدر ✓ - مار جرجس ✓ - محمد نجيب ✓ - عبد الناصر ✓ - الأوبرا ✓ - سعد زغلول ✓ - السادات ✓ - السيدة زينب ✓ All look correct — same as input. 5. Coordinate magnitudes check: lons ~31 (Cairo), lats ~30 — correct for CRS84 (WGS84 degrees). 6. The convex hull for each station with 3+ entrances yields a proper Polygon. The Sadat station has 5 entrance points, but the convex hull reduced to 4 points (one interior point). Let me check... Actually wait, Sadat's points: [31.235032, 30.043948], [31.236163, 30.044623], [31.236249, 30.044071], [31.236357, 30.043795], [31.236493, 30.044874]. The convex hull of these 5 points is a 4-vertex polygon. That's correct. Let me also verify that `Nasser` station is correct — its Arabic is `عبد الناصر` which matches the input. Good. Everything looks correct. Let me also quickly verify with a duckdb or geopandas check.
1:06
1:06
Bash
cd /work && python -c "
cd /work && python -c "
import geopandas as gpd
hulls = gpd.read_file('/work/cairo_metro_hulls.geojson')
print(f'Count: {len(hulls)}')
print(f'All geometry types: {hulls.geometry.geom_type.unique()}')
print(f'All names non-empty (en): {all(hulls.station_name_en.str.len() > 0)}')
print(f'All names non-empty (ar): {all(hulls.station_name_ar.str.len() > 0)}')
print(f'CRS: {hulls.crs}')
print()
# Compare Arabic names with input
orig = gpd.read_file('/work/cairo_metro_stations.geojson')
print(f'Input count: {len(orig)}')
match = hulls.station_name_ar.isin(orig.station_name_ar).all()
print(f'Arabic names preserved: {match}')
"
Count: 20 All geometry types: <ArrowStringArray> ['Polygon'] Length: 1, dtype: str All names non-empty (en): True All names non-empty (ar): True CRS: EPSG:4326 Input count: 20 Arabic names preserved: True
1:30
Let me also verify that the Sadat station hull is a proper polygon. The input has points: - [31.235032, 30.043948] - [31.236163, 30.044623] - [31.236249, 30.044071] - [31.236357, 30.043795] - [31.236493, 30.044874] The convex hull output is: [[31.236357, 30.043795], [31.235032, 30.043948], [31.236493, 30.044874], [31.236357, 30.043795]] That's only 3 points (triangle), which is correct — the hull of a multipoint with 5 points that has 3 extreme points forms a triangle. The hull is a Polygon. Good. Everything looks correct. Let me provide a summary.
1:30