.. _`Merge Table`:

.. _`org.sysess.data.table.mergetable`:

Merge Table
```````````

.. image:: merge.svg
   :width: 48


Merge tables on a shared index column




Documentation
:::::::::::::

Merge table on a shared `index column` in `input A` and `input B`.

A specific index can be present in either A or B, or in both A and B.
The `join operation` determines which rows to include in the output.

    - Intersection, output rows in A x B (cartesian product), where the two
      indices match. Corresponds to an intersection of indices from both A
      and B.

    - Index from A, output rows with index present in A and not in
      B. Also includes the `intersection`.

    - Index from B, output rows with index present in B and not in
      A. Also includes the `intersection`.

    - Union, output the rows for `index from A`, `index from B` and the
      `intersection` (once).  Corresponds to a union of indices from both A
      and B.

Output contains the index column (once) and one additional column for each
column in A and in B. Column names, except the index, that appear in both A
and B are made unique by adding a `suffix`. Rows with an index that is only
present in either of A or B will contain masked values (or NaN) in columns
missing data.

Example
=======

:Suffix A: _A

:Suffix B: _B

:A:

+----+-------+-----------+
| Id | Price | Inventory |
+====+=======+===========+
|  0 |    10 |         5 |
+----+-------+-----------+
|  1 |    15 |         0 |
+----+-------+-----------+
|  2 |    25 |         2 |
+----+-------+-----------+

:B:

+----+------+-------+
| Id | Sold | Price |
+====+======+=======+
|  1 |    1 |    10 |
+----+------+-------+
|  1 |    4 |    15 |
+----+------+-------+
|  2 |    3 |    25 |
+----+------+-------+
|  3 |    1 |    45 |
+----+------+-------+


:Intersection:

+----+---------+-----------+------+---------+
| Id | Price_A | Inventory | Sold | Price_B |
+====+=========+===========+======+=========+
|  1 |      15 |         0 |    1 |      10 |
+----+---------+-----------+------+---------+
|  1 |      15 |         0 |    4 |      15 |
+----+---------+-----------+------+---------+
|  2 |      25 |         2 |    3 |      25 |
+----+---------+-----------+------+---------+

:Index from A:

+----+---------+-----------+------+---------+
| Id | Price_A | Inventory | Sold | Price_B |
+====+=========+===========+======+=========+
|  0 |      10 |         5 |  NaN |     NaN |
+----+---------+-----------+------+---------+
|                   ... 3 intersection rows |
+----+---------+-----------+------+---------+

:Index from B:

+----+---------+-----------+------+---------+
| Id | Price_A | Inventory | Sold | Price_B |
+====+=========+===========+======+=========+
|                   ... 3 intersection rows |
+----+---------+-----------+------+---------+
|  3 |     NaN |       NaN |    1 |      45 |
+----+---------+-----------+------+---------+

:Union:

+----+---------+-----------+------+---------+
| Id | Price_A | Inventory | Sold | Price_B |
+====+=========+===========+======+=========+
|  0 |      10 |         5 |  NaN |     NaN |
+----+---------+-----------+------+---------+
|                   ... 3 intersection rows |
+----+---------+-----------+------+---------+
|  3 |     NaN |       NaN |    1 |      45 |
+----+---------+-----------+------+---------+


Definition
::::::::::


Input ports
===========

    **Input A**  table
        Input A

    **Input B**  table
        Input B


Output ports
============

    **Output**  table
        Output




Configuration
=============

    **Index column** (index)
        Index to join on, should exist in both input A and B.
    **Join operation** (operation)
        Join operation, determines which rows to output.
    **Suffix A** (suffix_a)
        Suffix for column names in A appearing in both A and B.
    **Suffix B** (suffix_b)
        Suffix for column names in B appearing in both A and B.







Examples
========

* :download:`MergeTable.syx </Examples/Sympathy/Data Processing/Structure/MergeTable.syx>`




Implementation
==============

.. automodule:: node_merge_tables
    :noindex:

.. class:: MergeTable
    :noindex: