Get trace name from hoverdata

Dash Python
2

curveNumber is the index of the object/dict/“trace” inside figure.data. The names are set with the name property, i.e.

app.layout = html.Div([
    dcc.Graph(id='graph', figure={
        'data': [
            {'x': [1], 'y': [3], 'name': 'This is Trace 1'},
            {'x': [1], 'y': [3], 'name': 'This is Trace 2'}
        ]})
])

One way to access it would be to index the element directly inside the callback:

@app.callback(...)
def respond_to_hover_data(hoverData):
     curve_number = hoverData[...]
     trace_name = app.layout['graph'].figure['data'][curve_number]['name']
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