streamlit-folium-example-app.py

"""
streamlit-folium-example-app

Run the following commands to launch the app:
$ pip install streamlit streamlit-folium
$ streamlit run streamlit-folium-example-app.py

"""

import time

import folium
import streamlit as st
from folium.features import Icon, Marker, PolyLine
from streamlit_folium import st_folium

#############
# Constants #
#############

# (lat, lng)
HANEDA_T1 = (35.5492863, 139.7844030)
TOKYO = (35.681093, 139.767043)

DEGREE_FORMAT = "%.5f"
DEGREE_STEP = 0.001

##############
# Init State #
##############

if not st.session_state.get("initialized"):
    initial_waypoints = [HANEDA_T1, TOKYO]
    for i, waypoint in enumerate(initial_waypoints):
        st.session_state["waypoint_{0}_lat".format(i)] = waypoint[0]
        st.session_state["waypoint_{0}_lng".format(i)] = waypoint[1]

    st.session_state.initialized = True

##############################
# Build Variables From State #
##############################

waypoints = []
i = 0
while True:
    waypoint_lat = st.session_state.get("waypoint_{0}_lat".format(i))
    waypoint_lng = st.session_state.get("waypoint_{0}_lng".format(i))
    if not waypoint_lat or not waypoint_lng:
        break
    waypoint = (waypoint_lat, waypoint_lng)
    waypoints.append(waypoint)
    i += 1

##########
# Inputs #
##########

with st.sidebar:
    for i, waypoint in enumerate(waypoints):
        st.write("Waypoint {0}".format(i))
        col1, col2 = st.columns(2)
        with col1:
            st.number_input(
                "lat",
                value=waypoint[0],
                key="waypoint_{0}_lat".format(i),
                format=DEGREE_FORMAT,
                step=DEGREE_STEP,
            )
        with col2:
            st.number_input(
                "lng",
                value=waypoint[1],
                key="waypoint_{0}_lng".format(i),
                format=DEGREE_FORMAT,
                step=DEGREE_STEP,
            )

st.write("# streamlit-folium example app")

col1, col2 = st.columns(2)

with col1:

    def on_remove_last_waypoint():
        last_index = len(waypoints) - 1
        if last_index < 0:
            return
        st.session_state["waypoint_{0}_lat".format(last_index)] = None
        st.session_state["waypoint_{0}_lng".format(last_index)] = None

    st.button("Remove last waypoint", on_click=on_remove_last_waypoint)

with col2:

    def on_clear_waypoints():
        i = 0
        while True:
            waypoint_lat = st.session_state.get("waypoint_{0}_lat".format(i))
            waypoint_lng = st.session_state.get("waypoint_{0}_lng".format(i))
            if not waypoint_lat or not waypoint_lng:
                break
            st.session_state["waypoint_{0}_lat".format(i)] = None
            st.session_state["waypoint_{0}_lng".format(i)] = None
            i += 1

    st.button("Clear waypoints", on_click=on_clear_waypoints)

###########
# Outputs #
###########

st.write("Click the map to add a waypoint:")


@st.cache_data(max_entries=3)
def create_folium_map(waypoints):
    m = folium.Map(location=TOKYO, zoom_start=11)
    m.add_child(folium.LatLngPopup())

    for i, waypoint in enumerate(waypoints):
        Marker(
            location=waypoint,
            popup="Waypoint {0}".format(i),
            icon=Icon(color="red" if i == 0 else "blue"),
        ).add_to(m)

    if len(waypoints) < 2:
        return m

    with st.spinner("Wait for it..."):
        # Request something to visualize
        time.sleep(1)

        for i in range(0, len(waypoints) - 1):
            PolyLine(
                [waypoints[i], waypoints[i + 1]],
                color="blue",
                weight=2.5,
                opacity=1,
            ).add_to(m)

    return m


st_map = st_folium(create_folium_map(waypoints))

if st_map.get("last_clicked"):
    last_clicked = st_map["last_clicked"]
    last_index = len(waypoints) - 1
    st.session_state["waypoint_{0}_lat".format(last_index + 1)] = last_clicked["lat"]
    st.session_state["waypoint_{0}_lng".format(last_index + 1)] = last_clicked["lng"]

    st_map["last_clicked"] = None
    st.rerun()


#########
# Debug #
#########

with st.expander("waypoints"):
    st.write(waypoints)

with st.expander("session_state"):
    st.write(st.session_state)