Manage Decay Rate¶

See also

MMA Key Terms - Decay Rates

A screen shot showing the Manage Decay Rate tool interface.

This is the geoprocessing interface for creating, storing, and modifying decay rate configuration files for use in MMA analyses.

Decay rates define how to discount activities at different destinations based on the cumulative impedance (usually travel time) from the origin.

Decay config file : File (.json): The .json config file in which to store decay rate details for later processing during accessibility summarization.
Name: A short name to identify the decay rate. The name is added to fields in the tables generated by the Summarize Accessibility tool, so a short string of a few characters is recommended.
Constant : Float: The constant term in the decay expression. Typical values are generally near or slightly above 1.0.
Coefficient : Float: The coefficient term in the decay expression. Typical values are less than zero.
Minimum impedance : Float, optional: The minimum impedance value to be evaluated as the impedance term in the decay formula. If blank, zero is assumed as the minimum impedance value.
Maximum impedance : Float, optional: The maximum impedance value to be evaluated as the impedance term in the decay formula. If blank, infinity is assumed as the maximum impedance value.
Exclude destinations below the minimum : Boolean, optional: Flag defining how to treat impedance values less than minimum impedance. If True, values less than minimum impedance are ignored. If False, values less than minimum impedance are treated as minimum impedance.
Exclude destinations beyond the maximum : Boolean, optional: Flag defining how to treat impedance values greater than maximum impedance. If True, values greater than maximum impedance are ignored. If False, values greater than maximum impedance are treated as maximum impedance.
Lower bound of result : Float, optional: Minimum value to return when evaluating the decay funtion specified by the decay config file with respect to a given impedance value. If no lower bound is provided, no lower bound constraint is placed on the decay formula (the fomula will typicall assymptotically approach zero when constant and coefficient values are in normal ranges.)
Upper bound of result : Float, optional: Maximum value to return when evaluating the decay funtion specified by the decay config file with respect to a given impedance value.
Description : String, optional: A longer description of the decay curve being defined. The description offers more detail than can be conveyed in the name parameter.