Full Package Reference
This page contains the full reference for the gerrychain package, and
is included primarily for the sake of developers trying to hunt down errors
or understand the codebase. For a more user-friendly introduction to the
usage of the package, please see the API Reference.
Accept
Chain
Grid
Metagraph
Tree
Constraints
Graph
This module provides a set of functions to help determine and manipulate the adjacency of geometries within a particular graph. The functions in this module are used internally to ensure that the geometry data that we are working with is sufficiently well-defined to be used for analysis.
Some of the type hints in this module are intentionally left unspecified because of import issues.
- gerrychain.graph.adjacency.intersections_with_neighbors(geometries)[source]
Generator yielding tuples of the form (id, {neighbor_id: intersection}). The intersections may be empty!
- Parameters
geometries (shapely.geometry.BaseGeometry) – A Shapeley geometry object.
- Returns
A generator yielding tuples of the form (id, {neighbor_id: intersection})
- Return type
Generator
- gerrychain.graph.adjacency.neighboring_geometries(geometries, tree=None)[source]
Generator yielding tuples of the form (id, (ids of neighbors)).
- Parameters
geometries (shapely.geometry.BaseGeometry) – A Shapeley geometry object to construct the tree from
tree (shapely.strtree.STRtree, optional) – A Sort-Tile-Recursive tree for spatial indexing. Default is None.
- Returns
A generator yielding tuples of the form (id, (ids of neighbors))
- Return type
Generator
- gerrychain.graph.adjacency.neighbors(df: <Mock name='mock.GeoDataFrame' id='140019760569600'>, adjacency: str) Dict[source]
- gerrychain.graph.adjacency.queen(geometries)[source]
- Parameters
geometries (shapely.geometry.BaseGeometry) – A Shapeley geometry object.
- Returns
The queen adjacency dictionary for the given collection of polygons.
- Return type
Dict
- gerrychain.graph.adjacency.rook(geometries)[source]
- Parameters
geometries (shapely.geometry.BaseGeometry) – A Shapeley geometry object.
- Returns
The rook adjacency dictionary for the given collection of polygons.
- Return type
Dict
- gerrychain.graph.adjacency.str_tree(geometries)[source]
Add ids to geometries and create a STR tree for spatial indexing. Use this for all spatial operations!
- Parameters
geometries (shapely.geometry.BaseGeometry) – A Shapely geometry object to construct the tree from.
- Returns
A Sort-Tile-Recursive tree for spatial indexing.
- Return type
shapely.strtree.STRtree
- gerrychain.graph.adjacency.warn_for_overlaps(intersection_pairs)[source]
- Parameters
intersection_pairs (Iterable) – An iterable of tuples of the form (id, {neighbor_id: intersection})
- Returns
A generator yielding tuples of intersection pairs
- Return type
Generator
- Raises
UserWarning if there are overlaps among the given polygons
This module contains functions for working with GeoDataFrames and Shapely geometries. Specifically, it contains functions for handling and reprojecting the Universal Transverse Mercator projection, and for identifying bad geometries within a given GeoDataFrame.
- exception gerrychain.graph.geo.GeometryError[source]
Bases:
ExceptionWrapper error class for projection failures. Changing a map’s projection may create invalid geometries, which may or may not be repairable using the .buffer(0) trick.
- gerrychain.graph.geo.explain_validity(geo) str[source]
Given a geometry that is shapely interpretable, explain the validity. Light wrapper around shapely’s explain_validity.
- Parameters
geo (shapely.geometry.BaseGeometry) – Shapely geometry object
- Returns
Explanation for the validity of the geometry
- Return type
str
- gerrychain.graph.geo.identify_utm_zone(df: <Mock name='mock.GeoDataFrame' id='140019760569600'>) int[source]
Given a GeoDataFrame, identify the Universal Transverse Mercator zone number for the centroid of the geometries in the dataframe.
- gerrychain.graph.geo.invalid_geometries(df)[source]
Given a GeoDataFrame, returns a list of row indices with invalid geometries.
- Parameters
df (
geopandas.GeoDataFrame) – The GeoDataFrame to examine- Returns
List of row indices with invalid geometries
- Return type
list of int
- gerrychain.graph.geo.reprojected(df)[source]
- Returns a copy of df, projected into the coordinate reference system of a suitable
- Parameters
df (
geopandas.GeoDataFrame) – The GeoDataFrame to reproject- Returns
A copy of df, projected into the coordinate reference system of a suitable UTM zone.
- Return type
geopandas.GeoDataFrame
- gerrychain.graph.geo.utm_of_point(point)[source]
Given a point, return the Universal Transverse Mercator zone number for that point.