code: def mapping_demo():
      @st.cache_data
      def from_data_file(filename):
          url = (
              "https://raw.githubusercontent.com/streamlit/"
              "example-data/master/hello/v1/%s" % filename
          )
          return pd.read_json(url)
  
      try:
          ALL_LAYERS = {
              "Bike Rentals": pdk.Layer(
                  "HexagonLayer",
                  data=from_data_file("bike_rental_stats.json"),
                  get_position=["lon", "lat"],
                  radius=200,
                  elevation_scale=4,
                  elevation_range=[0, 1000],
                  extruded=True,
              ),
              "Bart Stop Exits": pdk.Layer(
                  "ScatterplotLayer",
                  data=from_data_file("bart_stop_stats.json"),
                  get_position=["lon", "lat"],
                  get_color=[200, 30, 0, 160],
                  get_radius="[exits]",
                  radius_scale=0.05,
              ),
              "Bart Stop Names": pdk.Layer(
                  "TextLayer",
                  data=from_data_file("bart_stop_stats.json"),
                  get_position=["lon", "lat"],
                  get_text="name",
                  get_color=[0, 0, 0, 200],
                  get_size=10,
                  get_alignment_baseline="'bottom'",
              ),
              "Outbound Flow": pdk.Layer(
                  "ArcLayer",
                  data=from_data_file("bart_path_stats.json"),
                  get_source_position=["lon", "lat"],
                  get_target_position=["lon2", "lat2"],
                  get_source_color=[200, 30, 0, 160],
                  get_target_color=[200, 30, 0, 160],
                  auto_highlight=True,
                  width_scale=0.0001,
                  get_width="outbound",
                  width_min_pixels=3,
                  width_max_pixels=30,
              ),
          }
          st.sidebar.markdown("### Map Layers")
          selected_layers = [
              layer
              for layer_name, layer in ALL_LAYERS.items()
              if st.sidebar.checkbox(layer_name, True)
          ]
          if selected_layers:
              st.pydeck_chart(
                  pdk.Deck(
                      map_style=None,
                      initial_view_state={
                          "latitude": 37.76,
                          "longitude": -122.4,
                          "zoom": 11,
                          "pitch": 50,
                      },
                      layers=selected_layers,
                  )
              )
          else:
              st.error("Please choose at least one layer above.")
      except URLError as e:
          st.error(
              """
              **This demo requires internet access.**
              Connection error: %s
          """
              % e.reason
          )
  
imports: from urllib.error import URLError
  import pandas
  import pydeck
  import streamlit
  from streamlit.hello.utils import show_code
label_desc: Use image node_id 1 for calling a global function with example usage: mapping_demo() and returns: pd