Folium

Download this notebook from GitHub (right-click to download).

---

Demonstrates the use of Folium in Panel.

import folium as fm
import pandas as pd
import param
import panel as pn
import random
pn.extension(sizing_mode="stretch_width")

You can use Folium in a Panel App

def get_map(lat=20.5936832, long=78.962883, zoom_start=5):
    return fm.Map(location=[lat,long], zoom_start=zoom_start)

map = get_map()

pn.panel(map, height=400)

Interactive Panel app using Folium

Let build an interactive Panel application using Folium.

Lets define some data.

def get_df_aqi(lat_bounds=(10,30), long_bounds=(70,90), points_count=40):
    aqi = {
        "Latitude": [random.uniform(*lat_bounds) for _ in range(0,points_count)],
        "Longitude": [random.uniform(*long_bounds) for _ in range(0,points_count)],
        "AQI": [random.uniform(0,500) for _ in range(0,points_count)],
    }
    return pd.DataFrame(aqi)

df_aqi = get_df_aqi()
df_aqi.sample(5)

	Latitude	Longitude	AQI
24	13.222713	81.799040	361.690498
21	17.272171	75.131666	263.187930
20	10.900339	87.011256	123.523165
35	24.417011	85.485553	134.706631
37	12.117465	88.166950	184.005271

Lets define some functionality to add the data to the map as circles

def add_aqi_circles(map, df_aqi):
    green_p1  = fm.map.FeatureGroup()
    yellow_p1 = fm.map.FeatureGroup()
    orange_p1 = fm.map.FeatureGroup()
    red_p1    = fm.map.FeatureGroup()
    purple_p1 = fm.map.FeatureGroup()
    maroon_p1 = fm.map.FeatureGroup()

    for _, row in df_aqi.iterrows():
        if row.AQI<50:
            feature_group = green_p1
            fill_color = "green"
        elif row.AQI < 100:
            feature_group = yellow_p1
            fill_color = "yellow"
        elif row.AQI < 150:
            feature_group = orange_p1
            fill_color = "orange"
        elif row.AQI < 200:
            feature_group = red_p1
            fill_color = "red"
        elif row.AQI < 300:
            feature_group = purple_p1
            fill_color='purple'
        else:
            feature_group = maroon_p1
            fill_color = "maroon"

        feature_group.add_child(
            fm.CircleMarker(
                [row.Latitude, row.Longitude],
                radius=10, 
                fill=True,
                fill_color=fill_color,
                fill_opacity=0.7
            )
        )

    map.add_child(green_p1)
    map.add_child(yellow_p1)
    map.add_child(orange_p1)
    map.add_child(red_p1)
    map.add_child(purple_p1)

add_aqi_circles(map, df_aqi)
pn.panel(map, height=400)

Lets put it all together into an interactive app where the user can select the number of data points to generate and display.

class PanelFoliumMap(param.Parameterized):
    points_count = param.Integer(20, bounds=(10,100))
        
    def __init__(self, **params):
        super().__init__(**params)
        self.map = get_map()
        self.folium_pane = pn.pane.plot.Folium(sizing_mode="stretch_both", min_height=500, margin=0)    
        self.view = pn.Column(
            self.param.points_count,
            self.folium_pane,
            sizing_mode="stretch_both", height=500
        )
        self._update_map()

    @param.depends("points_count", watch=True)
    def _update_map(self):
        self.map = get_map()
        df_aqi = get_df_aqi(points_count=self.points_count)
        add_aqi_circles(self.map, df_aqi)
        self.folium_pane.object = self.map

        
app = PanelFoliumMap()
app.view

App

Lets wrap it into nice template that can be served via panel serve Folium.ipynb

pn.template.FastListTemplate(site="Panel", title="Folium", main=["This app demonstrates **how to use Folium with Panel**.", PanelFoliumMap().view]).servable();

This web page was generated from a Jupyter notebook and not all interactivity will work on this website. Right click to download and run locally for full Python-backed interactivity.

---

Download this notebook from GitHub (right-click to download).