Chorpleth图不显示颜色

Question

我有一个下面的Choropleth图代码。

m_6 = folium.Map(location=[35.6762,139.6503], tiles='cartodbpositron', zoom_start=12)

#Mark the store as a red circle
Circle(location=[35.6762,139.6503], radius=20, fill=True, color="red").add_to(m_6)

# Add a choropleth map to the base map
Choropleth(geo_data=districts['geometry'].__geo_interface__, 
           data=plot_dict['visit_prob'],
           key_on="feature.id", 
           fill_color='YlGnBu',
           legend_name='Trade Area of Store').add_to(m_6)

# Display the map
m_6

This is what my data looks like

情节是灰色的。颜色不出现。我不知道我错过了什么。