Simplify initial figures for sample app

rattail_dash/dashapp/sample.py

@@ -55,15 +55,6 @@ def sample_dash_app(config):
     # this date will be initially displayed, by default
     date = app.localtime().date()
 
-    empty_frame = pd.DataFrame(columns=['end_time', 
-                                        'terminal_id',
-                                        'subtotal'])
-
-    fig = px.bar(empty_frame, x="terminal_id", y="subtotal",
-                 barmode="group")
-
-    fig2 = px.line(empty_frame, x='end_time', y='subtotal')
-
     dashapp.layout = html.Div([
         html.H1("Hello {}".format(config.app_title()),
                 style={
@@ -97,12 +88,12 @@ def sample_dash_app(config):
 
         dcc.Graph(
             id='example-graph',
-            figure=fig
+            figure=px.bar(),
         ),
 
         dcc.Graph(
             id='example-graph2',
-            figure=fig2
+            figure=px.line(),
         ),
 
     ],