.. _`Filter rows in Table`:

.. _`org.sysess.sympathy.filters.columnfilternode`:

Filter rows in Table
~~~~~~~~~~~~~~~~~~~~

.. image:: filter.svg
   :width: 48


Filter column using Tables.



**Documentation**

Filter the rows of Value table producing a subset as the output Filtered
table.

Filtering takes place according to a comparison relation between the
elements of two chosen columns. One of the column, Value, chosen from the
Value table that will be filtered while the other, Reference, is chosen
from the Reference table.

The comparison relation can also be defined as a lambda function in the
configuration GUI or one of the predefined relations can be used.

The predefined relations are the following:
    - In
        keeps the row from Value table if the chosen Value column is also
        present anywhere in the Reference column.

    - Not in
        keeps the row from Value table if the chosen Value column is not
        present anywhere in the Reference column.

Alternatively, a custom filter function can be defined by writing a lambda
function. The lambda function will be called once for each item in the
selected Value column with the full Reference column available under the name
`ref` (or `C0`). The lambda function should return True or False.

See https://docs.python.org/3/tutorial/controlflow.html#lambda-expressions
for a description of lambda functions. Have a look at the :ref:`Table
API<tableapi>` to see all the available methods and attributes.


.. warning::

   The labels of this node has changed. The columns Reference, Value used
   to be called C0, C1 respectively. This can be good to keep in mind if
   you are used to the old names.


**Definition**


*Input ports*

    :port0:  table

        Reference Table

    :port1:  table

        Value Table


*Output ports*

    :port0:  table

        Filtered Table



*Configuration*:
    **Reference** (c0_column)
        Select the column in Reference Table, to use as reference column in the comparison.
    **Value** (c1_column)
        Select the column in Value Table, to compare with the reference column.
    **Operator** (filter_functions)
        Output Value rows where
    **Use custom filter function** (use_custom_predicate)
        Use a custom filter (predicate) function to filter.
    **Custom filter** (predicate_function)
        The predicate function to use when filtering.

.. automodule:: node_table_filter
    :noindex:

.. class:: ColumnFilterNode
    :noindex:




**Related nodes**

* :ref:`org.sysess.sympathy.data.table.selecttablerows`
* :ref:`org.sysess.sympathy.data.table.selecttablerowsfromtable`
* :ref:`org.sysess.sympathy.slice.columns.table`



**Example flows**

* :download:`FilterRowsInTable.syx </_examples/Sympathy/Data Processing/Select/FilterRowsInTable.syx>`