.. module:: emma.decay

.. toctree::
   :maxdepth: 2
   :caption: Contents:




Decay
===================
Decay rates express how travel costs influence behavior, discounting
the value of destinations based on how hard they are to reach (in terms
of time, monetary costs, etc.). Decay rates are utilized in the calculation
of accessibility scores and in trip distribution procedures.

This module provides classes and functions for configuring and applying
decay rates for use in emma modeling.


**Classes and Functions**
- `Decay`: a base class defining the basic parameters of decay rates.
  Various forms of decay rates, with distinct forms and applications,
  are defined as child classes:
  
  - `LinDecay`: linear
  
  - `ExpDecay`: exponential
  
  - `LogDecay`: logistic

  - `LogNormalDecay`: lognormal (probability density function)

  - `LogNormalDecay_cdf`: lognormal (cumulative density function)

- `dictToDecay`: constructs a Decay object from a dictionary.

- `decayToJson`: dumps a `Decay` object to a json file for storage

- `jsonToDecay`: creates a `Decay` object from a json file

- `vectorize`: a numpy vectorization wrapper that work with instance
  methods. Vectorizes `Decay.evalute` as `Decay.vevaluate`. However,
  purer vectorization can be acheived through `Decay.apply`.


Decay
'''''''''''
.. autoclass:: Decay
    :members:

LinDecay
'''''''''''
.. autoclass:: LinDecay
    :members:

ExpDecay
'''''''''''
.. autoclass:: ExpDecay
    :members:

LogDecay
'''''''''''
.. autoclass:: LogDecay
    :members:

LogNormalDecay
''''''''''''''''
.. autoclass:: LogNormalDecay
    :members:

LogNormalDecay_cdf
'''''''''''''''''''
.. autoclass:: LogNormalDecay_cdf
    :members:

Functions
''''''''''''
.. autofunction:: dictToDecay


.. autofunction:: decayToJson


.. autofunction:: jsonToDecay


.. autofunction:: vectorize



* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`