grouper_example5.py

import plotly.graph_objects as go
import plotly_express as px

# group the dataframe
group = df.groupby('types')

# create a blank canvas
fig = go.Figure()

# each group iteration returns a tuple
# (group name, dataframe)
for group_name, df in group:
  # in each loop, draw a time series then a regression line
    fig.add_trace(
        go.Scatter(
              x=df['dates']
            , y=df['count']
            , fill='tozeroy'
        ))
    # source: https://stackoverflow.com/questions/60204175/plotly-how-to-add-trendline-to-a-bar-chart
    # generate a regression line with px
    help_fig = px.scatter(df, x=df['dates'], y=df['count'], trendline="lowess")
    # extract points as plain x and y
    x_trend = help_fig["data"][1]['x']
    y_trend = help_fig["data"][1]['y']

    # add the x,y data as a scatter graph object
    fig.add_trace(
        go.Scatter(x=x_trend, y=y_trend, name='trend'))