.. index:: Core Operations; TimePeriodProportion
.. _core-operation-time_period_proportion:

TimePeriodProportion
====================

Sets the ``Value`` of each record to the proportion of the total time either elapsed or
remaining at the record's ``Time`` given a sequence interval ``period_start`` and
``period_end``.

Sets the ``Type`` of each record to ``Factor``.

Structure
---------

.. code-block:: json

    {
        "_schema": "TimePeriodProportion_1.0",
        "period_start": 1546300800,
        "period_end": 1577836800,
        "time_elapsed_basis": false
    }

Parameters
----------

+------------------------+----------+------------+------------------------------------------------------------------------------------------------------------------------------------+
|     Parameter Name     | Required |    Type    |                                                            Description                                                             |
+========================+==========+============+====================================================================================================================================+
| ``period_start``       | Yes      | ``double`` | The sequence value that denotes the beginning of the interval to be considered. This must be less than or equal to ``period_end``. |
+------------------------+----------+------------+------------------------------------------------------------------------------------------------------------------------------------+
| ``period_end``         | Yes      | ``double`` | The sequence value that denotes the end of the interval to be considered. This must be greater than or equal to ``period_start``.  |
+------------------------+----------+------------+------------------------------------------------------------------------------------------------------------------------------------+
| ``time_elapsed_basis`` | No       | ``bool``   | Default: ``false``. Determines if the proportions are computed based on time elapsed or time remaining in the time period.         |
+------------------------+----------+------------+------------------------------------------------------------------------------------------------------------------------------------+

Behaviour
---------

Records that occur before the ``period_start`` are considered to not have eroded time
within the specified interval. Records that occur after the ``period_end`` are considered
to have fully eroded the time within the time period. When ``period_start`` and
``period_end`` are equal, records occurring at that time are considered to have fully
eroded the time within the time period.