Pie Chart
=========

A :doc:`Callable </Callables/Callable>` for generating a pie chart.

Definition
----------

.. py:class:: controller.callable.outputter.PieChart(self, label_names: ColumnReference, x: ColumnReference, title: str)

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

    :param label_names: A column reference to find names of each pie section. 
    :type x: ColumnReference
    :param x: A column reference to find values for the pie sections. 
    :type y: ColumnReference
    :param title: The title of the chart.
    :type title: str

Parameters
----------

.. py:attribute:: label_names

    A column reference to find names of each pie section.

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

.. py:attribute:: x

    A column reference to find values for the pie sections.

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

.. py:attribute:: title

    The title of the chart.

    :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 pie chart in PNG format.
- The ``type`` column indicates the data type to be ``image/png``.

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

// TODO