File-Based Cache

For a variety of reasons, described below, UrbanSim uses two forms of file-based caches:

baseyear cache

Stores the attribute values read from the baseyear database. This includes data for the base year, and data for years before the base year (unrolled from data in the baseyear). This data is not modified during the simulation.

simulation cache

Stores the attribute values for datasets used during the simulation.

While the distinction between the read-only baseyear cache and read-write simulation cache is useful understanding the system, during simulation both caches form a single cache that UrbanSim datasets and models mine to gather data for the current and prior years.