enable multiple hover boxes for overlapping/multiple points

This has been tested in version 4.7.1.

When hover information is shown for points e.g. in a scatter plot, the following situations can occur:

• there are multiple points on exactly the same coordinates
• there are multiple points close to the same coordinates and the markers used to visualize those points overlap in the graph

Hover information for all those multiple points should be shown, especially in cases where the hover information includes additional data not shown directly in the graph.

The hvPlot library does this correctly: it shows stacked hover boxes for all the data points under the cursor. Plotly only shows one hover box and it is not clear which one.

I think this is an actual bug since it makes it easy to miss data and the hover information does not represent the actual data in the graph.

Here is an example using the Iris data set and Plotly:

import plotly.express as px
from bokeh.sampledata import iris
df = iris.flowers.copy()
fig = px.scatter(df, x="sepal_length", y="sepal_width", color="species",
                 opacity=0.4, hover_data=["petal_length", "petal_width"]
                )
fig.show()

This shows:

With hvPlot:

df.hvplot(kind="scatter", 
          x="sepal_length", y="sepal_width", by="species", 
          hover_cols=["petal_length", "petal_width"], 
          alpha=0.4)

Commencez par reproduire le comportement des points qui se chevauchent avec le jeu de données iris fourni et l’exemple px.scatter, puis comparez-le au résultat de hvPlot. Suivez la manière dont fig.show() rend les informations de survol pour les points coïncidents ou qui se chevauchent, et déterminez la limite du composant Plotly concerné. La tâche est considérée comme terminée lorsque tous les points sous le curseur reçoivent des informations de survol distinctes, avec une couverture de régression pour les chevauchements exacts et proches.