dataframe_plotter.py

"""The DataFramePlotter is an example of a Composable Extension for Panel

It was initially proposed by Haishiro and discussed in [Discourse 985]\
(https://discourse.holoviz.org/t/how-to-create-a-self-contained-custom-panel/985)
"""
import matplotlib.pyplot as plt
import pandas as pd
import panel as pn
import param
import seaborn as sns


class DataFramePlotter(pn.Column):
    """Extension Implementation"""

    column = param.Selector()
    # The _rename dict is used to keep track of Panel parameters to sync to Bokeh properties.
    # As column is not a property on the Bokeh model we should set it to None
    _rename = dict(pn.Column._rename, column=None)

    def __init__(self, data, **params):
        super().__init__(**params)

        self._plot_pane = pn.pane.Matplotlib(background="blue", sizing_mode="stretch_both")
        self[:] = [self.param.column, self._plot_pane]

        # Please note that the alternative of setting
        # @param.depends("column", watch=True)
        # on _update_plot_pane does not work.
        # See https://github.com/holoviz/panel/issues/1060
        self.param.watch(self._update_plot_pane, "column")

        columns = data.columns.values
        self.param.column.objects = columns
        # I need to set self.column to show a plot initially
        self.column = columns[0]

    # Make sure you don't use a function name already used by the Parent class.
    # For example _update_model is used by the Parent Class.
    def _update_plot_pane(self, _):
        # - I get exception if plt.close is below ax line. See https://github.com/holoviz/panel/issues/1482
        # - The plot does not change if I remove plot.close() fully.
        plt.close()

        ax = sns.distplot(df[self.column])
        self._plot_pane.object = ax.figure


if __name__.startswith("bokeh"):
    # Use the extension
    df = pd.DataFrame(data={"x": [1, 2, 3, 4, 5, 6, 7], "y": [1, 2, 2, 4, 5, 9, 7]})
    DataFramePlotter(df, width=300, height=300).servable()