I can successfully create a scatter plot based on a simple DataFrame that’s comprised of just 2 columns – Date and Value.

I can add some horizontal lines to highlight the start, lowest and highest values.

The scatter plot includes a trendline.

I know how to extract the r2 value but what I can’t figure out is how to show the r2 on the plot. I don’t really care where it goes although ideally it would be on the trendline.

Here’s what I have.

import plotly.express as px
from finance import get_df

if __name__ == "__main__":
    df = get_df()
    tl = px.scatter(df, x="Date", y="Value", trendline="ols")
    value = df["Value"]
    tl.add_hline(
        y=value.iloc[0],
        annotation_text="Start value",
        annotation_position="bottom left",
    )
    tl.add_hline(
        y=value.min(),
        line_color="red",
        annotation_text="Lowest value",
        annotation_position="bottom left",
    )
    tl.add_hline(
        y=value.max(),
        line_color="green",
        annotation_text="Highest value",
        annotation_position="bottom left",
    )
    tl.update_traces(
        hovertemplate="<i>Value</i>: £%{y:,.2f}",
        marker={"size": 8, "line": {"width": 1}},
        selector={"mode": "markers"},
    )
    # Here's the r-squared value
    r2 = px.get_trendline_results(tl).px_fit_results.iloc[0].rsquared
    tl.show()