`fig.update_traces(xaxis=..)` will destroy `hline` or `vline` objects on subplots

Summary

When the figure is created by make_subplots, updating traces' xaxis or yaxis will destroy hline or vlines from user's view.

Details

The following picture represents my figure created with subplots of 3 rows and 1 column. It has horizontal line added by figure.add_hline(y=0.0, ...).

def get_historical_charts(
    tournaments: list[TournamentSummary],
    max_data_points: int = 2000,
    window_sizes: tuple[int, ...] = DEFAULT_WINDOW_SIZES,
):
    # .... some dirty codes..

    figure.add_hline(    # <-------------------------------- ADDED hline
        y=0.0,
        line_color="red",
        line_dash="dash",
        row=1,
        col=1,
        label={
            "text": "Break-even",
            "textposition": "end",
            "font": {"color": "red"},
            "yanchor": "top",
        },
    )
    figure.update_layout(
        title="Historical Performance",
        hovermode="x unified",
        yaxis1={"tickformat": "$"},
        yaxis2={"tickformat": "%"},
        yaxis3={"tickformat": "$"},
    )
    figure.update_yaxes(row=3, col=1, patch={"type": "log"})
    # figure.update_traces(xaxis="x3")  # <------------------------------------- WILL CHANGE HERE
    return figure

However, I wanted to display vertical dash line on all subplots regardless of which graph you are focusing. I googled and found figure.update_traces(xaxis="x3") will make this work, but it destroyed hline. Notice that red dash line is disappeared on the second picture.

def get_historical_charts(
    tournaments: list[TournamentSummary],
    max_data_points: int = 2000,
    window_sizes: tuple[int, ...] = DEFAULT_WINDOW_SIZES,
):
    # .... some dirty codes..

    figure.add_hline(    # <-------------------------------- ADDED hline
        y=0.0,
        line_color="red",
        line_dash="dash",
        row=1,
        col=1,
        label={
            "text": "Break-even",
            "textposition": "end",
            "font": {"color": "red"},
            "yanchor": "top",
        },
    )
    figure.update_layout(
        title="Historical Performance",
        hovermode="x unified",
        yaxis1={"tickformat": "$"},
        yaxis2={"tickformat": "%"},
        yaxis3={"tickformat": "$"},
    )
    figure.update_yaxes(row=3, col=1, patch={"type": "log"})
    figure.update_traces(xaxis="x3")  # <------------- UPDATED XAXIS AND hline IS DESTROYED
    return figure

Note that there is only 1 line of difference from above two codes.

For full codes, you can refer my repository's code.

For bandaid, I can do figure.update_traces(xaxis="x1") instead, but it will destroy custom objects on second/third subplot. So this is not a fundamental resolution.

Personally I think showing horizontal or vertical dash line to indicate which x or y are you hovering is important. However, with current status you can potentially destroy custom plot objects like hline if you do that.

Thanks for reading this.

まず、make_subplots、add_hline、figure.update_traces(xaxis="x3") を使って問題を再現してください。リンクされている visualize.py に完全な例があります。update_traces が軸の割り当てをどのように変更するか、また subplot の hline オブジェクトがどのように表現されるかを追跡してください。トレースの軸を更新してもすべての subplot で hline と vline が保持され、報告された例で引き続き表示されれば完了です。