Added omitted code, changed wording

Author: fairlix

doc/python/lines-on-maps.md

@@ -111,17 +111,43 @@ fig.update_layout(
 
 fig.show()
 ```
-### High performance US Flight Paths Map
-If you can relinquish having individual styles for the flight paths (e.g. opacity), you can put multiple paths into one trace, which makes the map render much faster. 
+### Performance improvement: put many lines in the same trace
+For very large amounts (>1000) of lines, performance may become critcal. If you can relinquish setting individual line styles (e.g. opacity), you can put multiple paths into one trace. This makes the map render faster and reduces the script execution time and memory consumption. 
 
 Use ```None``` between path coordinates to create a break in the otherwise connected paths. 
 
 ```python 
-# ... omitted code: look at the previous "US Flight Paths Map" example
+import plotly.graph_objects as go
+import pandas as pd
+
+df_airports = pd.read_csv('https://raw.githubusercontent.com/plotly/datasets/master/2011_february_us_airport_traffic.csv')
+df_airports.head()
+
+df_flight_paths = pd.read_csv('https://raw.githubusercontent.com/plotly/datasets/master/2011_february_aa_flight_paths.csv')
+df_flight_paths.head()
+
+fig = go.Figure()
+
+fig.add_trace(go.Scattergeo(
+    locationmode = 'USA-states',
+    lon = df_airports['long'],
+    lat = df_airports['lat'],
+    hoverinfo = 'text',
+    text = df_airports['airport'],
+    mode = 'markers',
+    marker = dict(
+        size = 2,
+        color = 'rgb(255, 0, 0)',
+        line = dict(
+            width = 3,
+            color = 'rgba(68, 68, 68, 0)'
+        )
+    )))
+
+flight_paths = []
 lons = []
 lats = []
 for i in range(len(df_flight_paths)):
-    # None interrupts lines and makes it possible to draw multiple disconnected lines.
     lons += [df_flight_paths['start_lon'][i], df_flight_paths['end_lon'][i], None] 
     lats += [df_flight_paths['start_lat'][i], df_flight_paths['end_lat'][i], None]
 
@@ -135,7 +161,22 @@ fig.add_trace(
         opacity = 0.5 
     )
 )
-# ... omitted code: look at the previous "US Flight Paths Map" example
+
+fig.update_layout(
+    title_text = 'Feb. 2011 American Airline flight paths<br>(Hover for airport names)',
+    showlegend = False,
+    geo = go.layout.Geo(
+        scope = 'north america',
+        projection_type = 'azimuthal equal area',
+        showland = True,
+        landcolor = 'rgb(243, 243, 243)',
+        countrycolor = 'rgb(204, 204, 204)',
+    ),
+    height=700,
+)
+
+fig.show()
+
 ```