GeoPandas

Use GeoPandas for planar vector data represented as pandas-like GeoSeries and GeoDataFrame objects. This skill targets stable GeoPandas 1.2.0 (released 2026-09-28). The stable website currently carries a development build label; release-specific behavior below was checked against the v1.2.0 source and wheel.

Reproducible environment

GeoPandas 1.2.0 requires Python 3.11+, NumPy >=2, pandas >=2.2, Shapely >=2.1, pyproj >=3.7, pyogrio >=0.8, and packaging. The current pyproj wheel below requires Python 3.12+. This exact Python 3.12 snapshot was smoke-tested on 2026-10-01:

uv venv --python 3.12
uv pip install \
  "geopandas==1.2.0" \
  "numpy==2.5.3" \
  "pandas==3.0.6" \
  "shapely==2.1.2" \
  "pyproj==3.8.0" \
  "pyogrio==0.13.0" \
  "pyarrow==25.0.1" \
  "packaging==26.3"

Keep optional plotting and PostGIS packages pinned in the project lock as well. Do not mix binary geospatial packages from incompatible package channels.

Workflow

1. Inspect a vetted local layer with vector_inventory.py; retain source hashes.
2. Use crs_reprojection_plan.py to inspect candidate transformations. It plans only: execute an appropriate to_crs()/pyproj transformation separately.
3. Audit geometry with geometry_validity_report.py; compare simulated repair changes before requesting its optional new GeoPackage output.
4. Run the intended analysis with explicit predicates, CRS units, precision, and aggregation rules. spatial_join_audit.py measures join cardinality; it does not export joined features or perform a dissolve.
5. Use export_plan.py to inspect the proposed contract, then write and reopen the actual output separately. A successful plan has not written a file.
6. Review disclosure and generalization before sharing derived geodata/maps, using sensitive_coordinates_checklist.py when sensitive locations occur.

Examples below use synthetic or placeholder local inputs. File/database examples need the named dataset or service; PostGIS and tile-provider calls were reviewed against upstream contracts but were not exercised against a live service.

Safety and privacy contract

• Treat exact coordinates, addresses, parcel boundaries, trajectories, and small-area joins as sensitive. Default reports to counts, categories, coarse extents, and redacted identifiers. Generalize before publication.
• Never automatically load a URL, cloud URI, GDAL /vsi* path, archive, or geocode an address. Obtain explicit approval, validate provenance and hashes, then stage an unpacked local file in an isolated workspace.
• GDAL/OGR drivers, GEOS, PROJ, pyogrio, Shapely, pyproj, and their wheels are a native-code trust boundary. Prefer official wheels/conda-forge, record native versions, restrict drivers, and process untrusted data in a sandbox.
• Do not open macro-enabled office files or nested archives through permissive GDAL drivers. The bundled CLIs use an extension allowlist and reject archives.
• Read only named database secrets such as GEOPANDAS_POSTGIS_PASSWORD; use a secret manager or scoped environment variable. Never embed a password in a URL or source, print an engine/URL, or dump the environment.
• Every derived artifact needs source hashes/versions, CRS, operation parameters, predicate, join cardinality, precision/repair choices, and row-count checks.

Correctness gates

Apply these gates before trusting a result:

1. Identity and provenance — identify the source layer, stable feature key, duplicate IDs, row count, geometry column, parser/driver, and content hash.
2. Geometry state — count null, empty, invalid, mixed, Z/M, and collapsed geometries separately. None is missing; an empty Shapely geometry is real.
3. CRS semantics — require CRS metadata. set_crs() assigns metadata; to_crs() transforms coordinates. Never guess a CRS from coordinate ranges.
4. Units and operation — GeoPandas is planar. Geographic coordinates are angular; do not use them directly for buffer, distance, area, nearest joins, precision grids, or tolerances. Choose a fit-for-purpose local/equal-area CRS or a geodesic method.
5. Transform quality — inspect axis order, area of use, datum pipeline, expected accuracy, ballpark status, and missing grids. Keep PROJ network disabled unless the user explicitly approves grid retrieval.
6. Topology and precision — validate before and after repair/overlay. Pick a

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