.. _`Filter rows in Table`:

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

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

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


Filter the row in a table according to a comparison relation between the
elements of two column. One of the column, C1, is located in the Table
that will be filtered while the other, C0, is a column in a reference Table.

The comparison relation can 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:
    - Match C1 in C0
        keeps the row if the corresponding element in C1 exists in any row
        in C0.
    - Don't match C1 in C0
        keeps the row if corresponding element in C1 do not exist in any row
        in C0.

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 column C1
with the full column C0 available under the name `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.

:Ref. nodes: :ref:`Select rows in Tables`

*Ports*:

    **Inputs**:

        :port0: table

            Table with column, C0, with reference values
        :port1: table

            Table with column, C1

    **Outputs**:

        :port0: table

            Filtered Table

*Configuration*:

    **c0_column**
        Select the column in Table1, upper port, to use as reference column C0 in the comparison.
    **c1_column**
        Select the column in Table2, lower port, to use as object column C1 in the comparison.
    **filter_functions**
        All available pre-defined filter functions.
    **use_custom_predicate**
        Use a custom filter (predicate) function to filter.
    **predicate_function**
        The predicate function to use when filtering.

.. automodule:: node_table_filter

.. class:: ColumnFilterNode