Python Programming Guide: How to draw heat maps using Baidu Map API

Python Programming Guide: How to draw a heat map using Baidu Map API

Introduction:
Heat map is a chart used to visualize the distribution of data, which can visually display the intensity of data and distribution range. In the field of maps, heat maps can be used to display information such as activity intensity and population density in a certain area, providing an important basis for analysis and decision-making. This article will introduce how to draw heat maps using the Python programming language and Baidu Map API.

1. Preparation:
   First, we need to prepare the following tools and materials:
2. Python programming environment: Make sure you have installed Python and have basic programming knowledge.
3. Baidu Map Developer Account: Register a developer account on the Baidu Map open platform and obtain the API authorization key.

4. Install dependent libraries:
   Before starting programming, we need to install some Python libraries to help us draw heat maps. Execute the following instructions in the command line to install the required libraries:

   pip install requests
   pip install folium

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5. Get geographical coordinate data:
   Before drawing the heat map, we need to obtain some geographical coordinate data as an example. You can choose to use an existing dataset or obtain real geographic data through Baidu Map API. Here we take the longitude and latitude of various districts in Beijing as an example. These data can be obtained through the geocoding API provided by Baidu Map. For specific methods, please refer to the documentation of Baidu Map Open Platform.

import requests
import json

def get_coordinates(city):
    url = 'http://api.map.baidu.com/geocoder/v2/'
    params = {
        'address': city,
        'output': 'json',
        'ak': '你的API密钥',
    }

    response = requests.get(url, params)
    result = json.loads(response.text)

    if result['status'] == 0:
        coordinates = result['result']['location']
        return coordinates
    else:
        return None

city = '北京市'
coordinates = get_coordinates(city)
print(coordinates)

In the above code, we define a get_coordinates function to obtain the geographical coordinates of the specified city. It should be noted here that you fill in your API key in the params parameter so that you can normally request the Baidu Map interface.

4. Drawing heat maps:
   Drawing heat maps using the folium library is very simple and only requires a few lines of code to complete. folium is a Python library used to generate maps from the Leaflet JavaScript library, which provides many map-related functions and tools. The following is a sample code that uses the latitude and longitude data of various districts in Beijing that we obtained previously to draw a heat map.

import folium
from folium.plugins import HeatMap

beijing_coordinates = [39.9042, 116.4074]  # 北京市的经纬度坐标

m = folium.Map(location=beijing_coordinates, zoom_start=11)
heat_data = [[39.9042, 116.4074, 100], [39.9212, 116.4435, 80],
             [39.9490, 116.4539, 60], [39.9824, 116.3052, 50],
             [40.0485, 116.3024, 30], [39.9059, 116.3719, 20],
             [40.0024, 116.3383, 10], [39.9073, 116.3974, 5]]  # 示例的热力图数据

HeatMap(heat_data).add_to(m)

m.save('heatmap.html')

Code analysis:

• Line 3: Defines a latitude and longitude coordinate. Here we use the center coordinate of Beijing.
• Line 5: Create a folium.Map object. The location parameter specifies the center coordinates of the map. The zoom_start parameter specifies the zoom of the map. level.
• Line 6: Defines the data of the heat map. Each data point is represented by a list of length 3, which are latitude, longitude and weight. Depending on the actual situation, you can replace these sample data with your own data.
• Line 8: Use the HeatMap function to create a heat map object and add it to the map.
• Line 10: Save the map as an HTML file for easy viewing in the browser.

Summary:
This article introduces how to use the Python programming language and Baidu Map API to draw heat maps. First, we need to prepare the Python programming environment and Baidu Maps developer account. Then, we installed the necessary dependent libraries and obtained the geographical coordinate data. Finally, we drew a simple heat map example using the folium library. I hope this article can help you use Python to implement map data visualization functions.

References:

• Baidu Map Open Platform Documentation: https://lbsyun.baidu.com/index.php?title=webapi/guide/webservice-geocoding
• folium library official documentation: https://python-visualization.github.io/folium/

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