px.bar: when base is used, hoverlabel label should be "base+y: %y"

Minimal example:

tasks = pd.DataFrame([
    dict(Task="A", Start=0, Elapsed=10),
    dict(Task="B", Start=0, Elapsed=5),
    dict(Task="C", Start=5, Elapsed=10)
])
px.bar(tasks, base='Start', y='Elapsed', text='Task',)

Imagine an horizontal gantt-chart where x=Elapsed is Task duration in days. The issue is that Task C has “Elapsed=15” instead of “Elapsed=10”.

This also an issue in the graph_objects API in the default hover, but at least adding x as text shows the proper one.

go.Figure(data=[go.Bar(base=tasks['Start'], y=tasks['Elapsed'], text=tasks['Elapsed'])])

Note: In px.timeline it’s fine since user must give Finish=but in px.bar it’s looks pretty misleading to “change” x into finish 😃

If my Task lasts 10 days, the fact that it ends at day 15 is an internal positioning detail.

@nicolaskruchten is it just an oversight from https://github.com/plotly/plotly.py/issues/2585 or do you intend it this way?

[nicolaskruchten]

Still, I wonder why not make it the default behaviour of px.bar(base)

That’s a good idea but the implementation under the hood is a bit more complicated 😃

[Lxstr]

So the required code in the end works but removes all label text on the actual bars 😞 Is there any way to keep the labels on the bars?

hoverinfo="text",
hovertext = [f'In stock: {val}' for val in availability_df["InStock"]],

I also had to remove this line fig.update_traces(hovertemplate="%{x}")

I also wonder is this the most effective and CPU efficient way to do it? I feel like these lines to replicate what could be default seems unusual?

Ref: https://dev.to/fronkan/stacked-and-grouped-bar-charts-using-plotly-python-a4p