Plotly- dash :如何在plotly dash中为悬停函数编写交互式回调

import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output

# 创建Dash应用程序
app = dash.Dash(__name__)

# 定义应用程序的布局
app.layout = html.Div([
    dcc.Graph(
        id='graph',
        figure={
            'data': [
                {'x': [1, 2, 3], 'y': [4, 1, 2], 'type': 'bar', 'name': 'A'},
                {'x': [1, 2, 3], 'y': [2, 4, 5], 'type': 'bar', 'name': 'B'},
            ],
            'layout': {
                'title': 'Bar chart'
            }
        }
    ),
    html.Div(id='hover-data')
])

# 定义交互式回调函数
@app.callback(
    Output('hover-data', 'children'),
    [Input('graph', 'hoverData')]
)
def display_hover_data(hoverData):
    if hoverData is not None:
        return f"你悬停在点上的数据是：{hoverData['points'][0]['y']}"
    else:
        return "悬停在图表上以显示数据"

# 运行应用程序
if __name__ == '__main__':
    app.run_server(debug=True)