sdc-catchment

Floating catchment area (FCA) spatial-accessibility metrics — 2SFCA, E2SFCA, KD2SFCA, 3SFCA, modified-2SFCA, balanced FCA, and commute-based FCA, all as parameter variations of a single catchment_ratio().

Part of the Social Data Commons toolkit. Extracted from sdc_core.catchment; the Python replacement for the R catchment package.

Install

uv add sdc-catchment   # or: pip install sdc-catchment

Quickstart

Access of three consumers to two providers, under a gaussian distance-decay:

import numpy as np
import pandas as pd
from sdc_catchment import catchment_ratio, euclidean_cost

consumers = pd.DataFrame({"geoid": ["c1", "c2", "c3"], "value": [100.0, 100.0, 100.0]})
providers = pd.DataFrame({"geoid": ["p1", "p2"], "value": [10.0, 10.0]})
cost = euclidean_cost(np.array([[0, 0], [1, 0], [2, 0]]), np.array([[0, 0], [2, 0]]))

access = catchment_ratio(consumers, providers, cost, weight="gaussian", scale=1.0)
print(access.to_string())
# c1    0.065179
# c2    0.069641
# c3    0.065179

The central consumer (c2) has the highest access; decay weights each provider by distance.

Public API

• catchment_ratio — accessibility ratio under a chosen FCA variant.
• catchment_weight — distance-decay weight matrix builder.
• catchment_connections / catchment_network — provider/consumer connectivity.
• euclidean_cost — pairwise Euclidean cost matrix.
• KERNELS, WeightSpec — kernel registry and weight-spec type.

Documentation

• Introduction to floating catchment areas
• Case study
• API reference