Lineplot with markers in holoviews (or hvplot)

Question

I know how to make a lineplot with holoviews / hvplot.
But how can I add markers of the datapoints to my line plot?

The plot should look something like this:

Here's some sample code:

# import libraries
import numpy as np
import pandas as pd

import hvplot.pandas
import holoviews as hv

# create sample data
df = pd.DataFrame({
    'date_col': pd.date_range(start='1-1-2020', freq='m', periods=12),
    'value_col': np.random.normal(size=12),
})

Answer 1

You can add markers to a line plot by combining it with a scatterplot.

In Holoviews this is called an overlay and this overlay can be done by using the * symbol.

The Hvplot solution:

# create a line plot
line_plot = df.hvplot.line(
    x='date_col', 
    y='value_col',
)

# scatter plot with some extra styling options just for fun
scatter_plot = df.hvplot.scatter(
    x='date_col',
    y='value_col',
).opts(color='black', size=20, marker='o')

# overlay the scatterplot on the lineplot to get markers added to your lineplot
line_plot * scatter_plot

The Holoviews solution:

# overlay the scatter plot on the curve by using the * symbol
hv.Curve(df) * hv.Scatter(df).opts(color='black', size=20, marker='o')