Graph Operations

class Graph:
    @classmethod
    def from_file(
        cls, 
        filename: str, 
        adjacency: str = "rook"
    ) -> "Graph":
        """
        Create a Graph from a shapefile or GeoJSON file.
        
        Parameters:
        - filename (str): Path to shapefile (.shp) or GeoJSON file
        - adjacency (str): Adjacency type - "rook" or "queen"
        
        Returns:
        Graph: New graph with geographic data and adjacency edges
        """

    @classmethod
    def from_geodataframe(
        cls, 
        dataframe, 
        adjacency: str = "rook"
    ) -> "Graph":
        """
        Create a Graph from a GeoPandas GeoDataDF.
        
        Parameters:
        - dataframe (GeoDataFrame): GeoPandas dataframe with geometry
        - adjacency (str): Adjacency type - "rook" or "queen"
        
        Returns:
        Graph: New graph with geographic data and adjacency edges
        """

    @classmethod
    def from_networkx(cls, graph) -> "Graph":
        """
        Create a Graph from an existing NetworkX graph.
        
        Parameters:
        - graph: NetworkX graph object
        
        Returns:
        Graph: New GerryChain Graph wrapping the NetworkX graph
        """

    @classmethod
    def from_json(cls, json_file: str) -> "Graph":
        """
        Load a Graph from a JSON file.
        
        Parameters:
        - json_file (str): Path to JSON file
        
        Returns:
        Graph: Loaded graph
        """

from gerrychain import Graph

# From shapefile
graph = Graph.from_file("precincts.shp", adjacency="queen")

# From GeoDataFrame  
import geopandas as gpd
gdf = gpd.read_file("districts.geojson")
graph = Graph.from_geodataframe(gdf, adjacency="rook")

def join(self, other_dataframe, columns: List[str] = None) -> None:
    """
    Join additional data to graph nodes.
    
    Parameters:
    - other_dataframe (DataFrame): Data to join to graph nodes
    - columns (List[str], optional): Specific columns to join
    
    Returns:
    None: Modifies graph in place
    """

def lookup(self, key: str, target_column: str) -> Dict:
    """
    Create a lookup mapping from key column to target column.
    
    Parameters:
    - key (str): Column name to use as lookup key
    - target_column (str): Column name for lookup values
    
    Returns:
    Dict: Mapping from key values to target values
    """

def to_json(
    self, 
    json_file: str, 
    *, 
    include_geometries_as_geojson: bool = False
) -> None:
    """
    Save graph to JSON file.
    
    Parameters:
    - json_file (str): Path to output JSON file
    - include_geometries_as_geojson (bool): Whether to include geometries as GeoJSON
    
    Returns:
    None: Saves graph to file
    """

def issue_warnings(self) -> None:
    """
    Check graph for common issues and warn about problems.
    
    Returns:
    None: Prints warnings to console
    """

import pandas as pd

# Join election data
election_data = pd.read_csv("election_results.csv")
graph.join(election_data, columns=["SEN18D", "SEN18R"])

# Create lookup for population by district
pop_lookup = graph.lookup("GEOID", "population")

def neighbors(self, node_id: NodeId) -> List[NodeId]:
    """
    Get neighbors of a specific node.
    
    Parameters:
    - node_id (NodeId): ID of the node
    
    Returns:
    List[NodeId]: List of neighboring node IDs
    """

def reprojected(geometry, crs_from: str, crs_to: str):
    """
    Reproject geometric data between coordinate reference systems.
    
    Parameters:
    - geometry: Geometric data to reproject
    - crs_from (str): Source CRS (e.g., "EPSG:4326")  
    - crs_to (str): Target CRS (e.g., "EPSG:3857")
    
    Returns:
    Reprojected geometry
    """

class GeometryError(Exception):
    """Raised when geometric operations fail."""

def add_edges_from_file(graph: Graph, filename: str) -> None:
    """
    Add adjacency edges from an external file.
    
    Parameters:
    - graph (Graph): Graph to modify
    - filename (str): Path to adjacency file
    
    Returns:
    None: Modifies graph in place
    """

def neighbors_of_component(graph: Graph, component: Set[NodeId]) -> Set[NodeId]:
    """
    Find all neighbors of a connected component.
    
    Parameters:
    - graph (Graph): The graph
    - component (Set[NodeId]): Set of nodes forming a component
    
    Returns:
    Set[NodeId]: Set of neighboring nodes outside the component
    """

def neighbors_of_node(graph: Graph, node_id: NodeId) -> Set[NodeId]:
    """
    Find neighbors of a single node.
    
    Parameters:
    - graph (Graph): The graph
    - node_id (NodeId): ID of the node
    
    Returns:
    Set[NodeId]: Set of neighboring node IDs
    """

NodeId = Union[int, str]  # Graph node identifier
AdjacencyType = Literal["rook", "queen"]  # Spatial adjacency types