geosnap.analyze.isochrones_from_gdf

geosnap.analyze.isochrones_from_gdf(origins, threshold, network, network_crs=None, reindex=True, hull='shapely', ratio=0.2, allow_holes=False, use_edges=True)

Create travel isochrones for several origins simultaneously

Parameters:

originsgeopandas.GeoDataFrame

a geodataframe containing the locations of origin point features

threshold: float

maximum travel cost to define the isochrone, measured in the same impedance units as edges_df in the pandana.Network object.

networkpandana.Network

pandana Network instance for calculating the shortest path isochrone for each origin feature

network_crsstr, int, pyproj.CRS (optional)

the coordinate system used to store x and y coordinates in the passed pandana network. If None, the network is assumed to be stored in the same CRS as the origins geodataframe

reindexbool

if True, use the dataframe index as the origin and destination IDs (rather than the node_ids of the pandana.Network). Default is True

hullstr, {‘libpysal’, ‘shapely’}

Which method to generate container polygons (concave hulls) for destination points. If ‘libpysal’, use libpysal.cg.alpha_shape_auto to create the concave hull, else if ‘shapely’, use shapely.concave_hull. Default is libpysal

ratiofloat

ratio keyword passed to shapely.concave_hull. Only used if hull=’shapely’. Default is 0.3

allow_holesbool

keyword passed to shapely.concave_hull governing whether holes are allowed in the resulting polygon. Only used if hull=’shapely’. Default is False.

use_edges: bool

If true, use vertices from the Network.edge_df to make the polygon more accurate by adhering to roadways. Requires that the ‘geometry’ column be available on the Network.edges_df, most commonly by using geosnap.io.get_network_from_gdf

Returns:

GeoPandas.DataFrame

polygon geometries with the isochrones for each origin point feature