title: plotly Dash: Assigning indicator graph to dropdown values
body: <p>I am trying to assign an indicator graph to a dropdown list. The dropdown works when another graph type such as pie or bar is used, but I cannot get the indicator graph to change when an option is selected on the dropdown.
  This is the working example for the pie chart I made</p>
  <pre><code>    @app.callback(
      Output(component_id='pie_graph2', component_property='figure'),
      [Input(component_id='pie_dropdown_percentage', component_property='value')]
  )
  def update_graph(year):
      piechart_qual2 =  px.bar(pie_melt_prevalence[pie_melt_prevalence['lau115nm'] == str(year)], x=&quot;namepie2&quot;, y=&quot;valuepie2&quot;,
                             title = &quot;population level by percentage&quot;, animation_frame='year', hover_name=&quot;valuepie2&quot;, width=800,height=800,
                     
                    )
      return piechart_qual2
  </code></pre>
  <p>This is where I am struggling making the same dropdown work for the indicator graph</p>
  <pre><code>meanwage = df['weeklygrosspaymean'].tail(1).iloc[0].astype(float)
  
  @app.callback(
      Output(component_id='pie_graph3', component_property='figure'),
      [Input(component_id='pie_dropdown_percentage', component_property='value')]
  )
  def update_graph(year):
      fig = go.Figure(go.Indicator(
          mode = &quot;number+delta&quot;,
          value = meanwage,
          number = {'prefix': &quot;£&quot;},
          delta = {'position': &quot;top&quot;, 'reference': 320},
          domain = {'x': [0, 1], 'y': [0, 1]}))
      fig.update_layout(paper_bgcolor = &quot;lightgray&quot;)
      return fig
  </code></pre>
  <p>In the dashboard, the indicator graph does appear, it just doesn’t change when I select the dropdown
  Any guidance would be hugely appreciated.
  Thank you</p>