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lines 5-73 of file: xrst/table/weight_grid_table.xrst
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{xrst_begin weight_grid_table}

The Weight Grid Table
#####################

Discussion
**********
This table specifies the age-time weighting functions on a grid.
It has the following columns:

weight_grid_id
**************
This column has type ``integer`` and is the primary key for
the ``weight_grid`` table.
Its initial value is zero, and it increments by one for each row.

weight_id
*********
This column has type ``integer`` and is a
:ref:`weight_table@weight_id` in the weight table.
Each *weight_id* value corresponds to a different weighting.

age_id
******
This column has type ``integer`` and is a
:ref:`age_table@age_id` in the age table.
Each *age_id* value corresponds to a specific age.

time_id
*******
This column has type ``integer`` and is a
:ref:`time_table@time_id` in the time table.
Each *time_id* value corresponds to a specific time.

weight
******
This column has type ``real`` .
For each row in the table, the value in this column
is the weighting, at the corresponding age and time,
and for the specified *weight_id* ,

Positive
========
If the *weight_id* for a row appears in the
:ref:`data table <data_table@weight_id>` or the
:ref:`avgint table <avgint_table@weight_id>` ,
the corresponding *weight* must be positive (greater than zero).

Rectangular Grid
****************
For each fixed value of *weight_id*
the set of *age_id* , *time_id* pairs is rectangular.
In other words,
if an *age_id* value appears,
it appears once with each *time_id*
that appears with this *weight_id* .
This also means,
if a *time_id* value appears,
it appears once with each *age_id*
that appears with this *weight_id* .
{xrst_toc_hidden
    example/table/weight_grid_table.py
}
Example
*******
The file :ref:`weight_grid_table.py-name`
contains an example ``weight_grid`` table.

{xrst_end weight_grid_table}