Computing walking distance to transit stops

In this example we show how to use Polaris-Studio to compute the distance to transit stops from each location.

The user can compute distances to arbitrary stops, or automatically select all stops for which there are BRT or rail services

Imports

from pathlib import Path

import folium
import numpy as np

from polaris import Polaris
from polaris.network.tools.tod_distance import DistanceToTransit
from polaris.utils.database.db_utils import read_and_close

Data Sources

# Open the demand database for analysis
model_fldr = "/tmp/Bloomington"
# model_fldr = r"C:\temp_container\Bloomington"

network = Polaris.from_dir(Path(model_fldr)).network

DtT = DistanceToTransit(path_to_file=network.path_to_file)

We can get the list of locations locations within a certain distance from a list of stops

locations = DtT.locations_within_distance(1000, [2000000000001])
print(locations)

euclidean_locations = DtT.locations_within_distance(1000, [2000000000001], use_routed_distance=False)

[41, 42, 61, 62, 63, 64, 197, 198, 285, 286, 419, 420, 471, 472, 979, 980, 981, 982, 983, 984, 1053, 1054, 1057, 1058, 1125, 1126, 1149, 1150, 1165, 1166, 1167, 1168, 1339, 1340, 2037, 2038, 2039, 2040, 2047, 2048, 2163, 2164, 2219, 2220, 2351, 2352, 2353, 2354, 2585, 2586, 2692, 2693, 2694, 2695, 2696, 2697, 2700, 2701, 2714]

We can also set the stops we are interested in, by providing a list, detecting BRT stops automatically, and/or detecting rail stops automatically

# For the example, we choose the stops for an arbitrary route
my_stops = np.array(
    [
        2000000000001,
        2000000000002,
        2000000000003,
        2000000000004,
        2000000000005,
        2000000000006,
        2000000000007,
        2000000000008,
        2000000000009,
        2000000000010,
        2000000000011,
    ],
    np.int64,
)
DtT.set_tod_stops(tod_stops=my_stops, get_brt=False, get_rail=False)

# After setting the stops, the user can compute the distances from each location to their nearest "relevant" stop
distances = DtT.build_tod_distances()

# Some locations don' have any access to transit, so we can filter them out
distances = distances[distances.distance_to_tod < np.inf]

And we can plot this path on the network

data = network.data_tables
with read_and_close(network.path_to_file, spatial=True) as conn:
    loc_layer = data.plotting_layer("Location", conn).merge(distances, on="location")
    stops = data.plotting_layer("Transit_Stops", conn).query("stop_id in @my_stops")

Plotting results

In this case, we will use a custom color ramp to show the data in a more meaningful way

Cusom color ramp

import branca.colormap as cm

mmin = distances.distance_to_tod.min()
mmax = distances.distance_to_tod.max()
step = (mmax - mmin) / 4
lin_scale = cm.LinearColormap(
    ["green", "yellow", "orange", "red"],
    index=[mmin / mmax, (mmin + step) / mmax, (mmin + 3 * step) / mmax, mmax / mmax],
)

Plotting

tstops = folium.FeatureGroup("stops")
locations = folium.FeatureGroup("Locations")

for location_id, row in loc_layer.iterrows():
    point = eval(row.geo.replace("POINT", "").replace(" ", ","))
    point = (point[1], point[0])
    _ = folium.vector_layers.CircleMarker(
        point,
        popup=f"<b>Location:{location_id}, Distance: {int(row.distance_to_tod):,}</b>",
        color=lin_scale(row.distance_to_tod / mmax),
        radius=2,
        fill=True,
        fillColor=lin_scale(row.distance_to_tod / mmax),
        fillOpacity=1.0,
    ).add_to(locations)

for stop_id, row in stops.iterrows():
    point = eval(row.geo.replace("POINT", "").replace(" ", ","))
    point = (point[1], point[0])
    _ = folium.vector_layers.CircleMarker(
        point,
        popup=f"<b>Stop: {stop_id}</b>",
        color="black",
        radius=6,
        fill=True,
        fillColor="black",
        fillOpacity=1.0,
    ).add_to(tstops)

a, b = tstops.get_bounds()
map_center = list((np.array(a) + np.array(b)) / 2)

map_osm = folium.Map(location=map_center, zoom_start=12, tiles="cartodb positron")
locations.add_to(map_osm)
tstops.add_to(map_osm)
folium.LayerControl().add_to(map_osm)
map_osm

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