Shapely - Planar Geometry

Shapely is the engine behind GeoPandas and many other GIS tools. It focuses on the geometry itself: calculating intersections, unions, distances, and checking spatial relationships (like "is this point inside this polygon?").

When to Use

• Precise manipulation of 2D geometric shapes.
• Performing set-theoretic operations (Intersection, Union, Difference).
• Checking spatial predicates (Contains, Within, Intersects, Touches).
• Cleaning and validating "dirty" geometry (fixing self-intersections).
• Calculating geometric properties (Area, Length, Centroid, Bounds).
• Generating buffers or simplifying complex lines.
• Linear referencing (finding points along a line).

Reference Documentation

Official docs: https://shapely.readthedocs.io/
GEOS (Engine): https://libgeos.org/
Search patterns: shapely.geometry, shapely.ops.unary_union, shapely.validation.make_valid