Correlation Plot
================

A :doc:`Callable </Callables/Callable>` for generating a pairwise correlation plot (heatmap).

Definition
----------

.. py:class:: controller.callable.outputter.CorrelationPlot(self, column_names: list[ColumnReference], title: str)

    :callable name: ``correlation_plot``
    :callable type: :doc:`Outputter </Callables/Types/Outputter>`

    :param column_names: A list of column references where the selected columns are compared for pairwise correlation.
    :type column_names: list[ColumnReference]
    :param title: The title of the plot.
    :type title: str

Parameters
----------

.. py:attribute:: column_names

    A list of column references where the selected columns are compared for pairwise correlation.

    :type: list[ColumnReference]
    :required: True
    :choices: All columns in the target DataFrame

.. py:attribute:: title

    The title of the plot.

    :type: str
    :required: True

Output
------

A DataFrame is returned where it contains two columns matching the output conventions of an Outputter.

- The ``data`` column contains the generated correlation plot (heatmap) in PNG format.
- The ``type`` column indicates the data type to be ``image/png``.

Example configuration
---------------------

.. code-block:: javascript

    {
        "name": "foo",
        "callable": "correlation_plot",
        "params": {
            "column_names": [
                "$get_students_submissions.student.admission_year"
                "$get_students_submissions.student.program"
                "$get_students_submissions.submission.score"
            ],
            "title": "Correlation"
        }
    }