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@sjsrey sjsrey released this 12 Jul 17:23
v1.1.1
05ec9f7

The PySAL spatial access package aims to make it easy for analysis to calculate measures of spatial accessibility. This work has traditionally had two challenges:

  1. to calculate accurate travel time matrices at scale and
  2. to derive measures of access using the travel times and supply and demand locations.

Our project addresses both of these challenges.

  • We implement classic spatial access models, allowing easy comparison of methodologies and assumptions.
  • We support spatial access research by providing pre-computed travel time matrices and share code for computing new matrices at scale.
  • We also developed a simple web app that runs the package on Amazon Web Services, allowing users to explore results without installing the package. We think this is a fun new strategy for trying new analysis methods, and hope that it will make the package more accessible to professionals.

This access models implement include:

  • Floating Catchment Areas (FCA): For each provider, this is the ratio of providers to clients within a given travel time to the provider (Huff 1963, Joseph and Bantock 1982, and Luo 2004).
  • Two-Stage FCAs (2SFCA): Calculated in two steps for a given travel time to the provider: 1) for each provider, the provider-to-client ratio is generated, 2) for each point of origin, these ratios are then summed (Luo and Wang 2002, and Wang and Luo 2005).
  • Enhanced 2SFCA (E2SFCA): 2SFCA but with less weight to providers that are still within the travel threshold but at larger distances from the point of origin (Luo and Qi 2009).
  • Three-Stage FCA (3SFCA): adds distance-based allocation function to E2SFCA (Wan, Zou, and Sternberg, 2012).
  • Rational Agent Access Model (RAAM) (Saxon and Snow 2019).
  • Access Score: This is a weighted sum of access components like distance to provider and relative importance of provider type (Isard 1960).

The package is implemented as a single class with a number of helper functions. According to PySAL tradition, we have also developed a broad set of tutorials and examples.

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