Plots the weighted adjacency graph by how often precincts coocur. If an argument
to counties is provided, it subsets the edges to plot to those that cross over the county boundary.
A SpatialPolygonsDataFrame, sf object, or redist_map. Required.
plans
A `redist_plans` object or matrix of redistricting plans, where each
column indicates a plan and each
counties
unquoted name of a column in `shp` or a vector of county assignments. Subsets to
edges which cross this boundary if supplied.
ref
Plot reference map? Defaults to TRUE which gets the existing plan from
adj
A zero-indexed adjacency list. Extracted from `shp` if `shp` is a `redist_map`.
Otherwise created with redist.adjacency if not supplied. Default is NULL.