如何在python中使用Dash将文本悬停在表格上

Question

我正在使用Dash创建仪表板，我想通过悬停表格来显示文本，以便我可以使用该信息进一步更新不同的图形，以下是我正在使用的示例数据的代码

import dash
import dash_core_components as dcc
import dash_html_components as html
import plotly.graph_objs as go
from dash.dependencies import Input, Output
import pandas as pd
import json


df = pd.read_csv('https://raw.githubusercontent.com/plotly/datasets/master/2014_usa_states.csv')

# Launch the application:
app = dash.Dash()

# Create a Dash layout that contains a Graph component:


app.layout = html.Div([
    html.Div([
    dcc.Graph(
        id='table',
        figure={
            'data': [
                    go.Table(
                            header=dict(values=list(df.columns),
                                        fill = dict(color='#C2D4FF'),
                                        align = ['left'] * 5),

                            cells=dict(values=[df.Rank, df.State, df.Postal, df.Population],
                                       fill = dict(color='#F5F8FF'),
                                       align = ['left'] * 5)
                            )
            ],
            'layout': go.Layout(
                title = 'US - Population',
                hovermode='closest'
            )
        }
    )], style={'width':'60%', 'float':'left'}),

    html.Div([
    html.Pre(id='hover-data', style={'paddingTop':35})
    ], style={'width':'30%'})
])

@app.callback(
    Output('hover-data', 'children'),
    [Input('table', 'hoverData')])
def callback_image(hoverData):
    return json.dumps(hoverData, indent=2)

if __name__ == '__main__':
    app.run_server()

但是它没有报告任何事情。请帮助我。