Python programming to analyze the coordinate conversion function in Baidu Map API documentation

Python programming analyzes the coordinate conversion function in Baidu Map API documentation

Introduction:
With the rapid development of the Internet, the map positioning function has become an indispensable part of modern people's lives. As one of the most popular map services in China, Baidu Maps provides a series of APIs for developers to use. This article will use Python programming to analyze the coordinate conversion function in Baidu Map API documentation and give corresponding code examples.

1. Introduction
During development, we sometimes involve coordinate conversion issues. Baidu Map API provides a set of coordinate conversion functions that can convert coordinates from different systems to each other.

2. Function Overview
The coordinate conversion functions mentioned in the Baidu Map API document mainly include the following items:

1. WGS84 coordinates to Baidu coordinates (GCJ-02)
2. Baidu coordinates (BD-09) to WGS84 coordinates
3. WGS84 coordinates to Mars coordinates (GCJ-02)
4. Mars coordinates (GCJ-02) to WGS84 coordinates

3. Python code example
Next, we use Python programming to demonstrate how to use Baidu Map API to achieve coordinate conversion.

First, we need to introduce the requests library to send HTTP requests, and the json library to parse the response results. These two libraries can be installed through the following command:

pip install requests

Then, we can create a class named BaiduMap to encapsulate the coordinate conversion function. The specific code is as follows:

import requests
import json

class BaiduMap:
    def __init__(self, ak):
        self.ak = ak  # 百度地图API的密钥

    def wgs84_to_bd09(self, lng, lat):
        url = "http://api.map.baidu.com/geoconv/v1/?coords={},{}&from=1&to=5&ak={}".format(lng, lat, self.ak)
        response = requests.get(url)
        data = json.loads(response.text)
        if data["status"] == 0:
            return data["result"][0]["x"], data["result"][0]["y"]
        else:
            return None

    def bd09_to_wgs84(self, lng, lat):
        url = "http://api.map.baidu.com/geoconv/v1/?coords={},{}&from=5&to=1&ak={}".format(lng, lat, self.ak)
        response = requests.get(url)
        data = json.loads(response.text)
        if data["status"] == 0:
            return data["result"][0]["x"], data["result"][0]["y"]
        else:
            return None

    def wgs84_to_gcj02(self, lng, lat):
        url = "http://api.map.baidu.com/geoconv/v1/?coords={},{}&from=1&to=3&ak={}".format(lng, lat, self.ak)
        response = requests.get(url)
        data = json.loads(response.text)
        if data["status"] == 0:
            return data["result"][0]["x"], data["result"][0]["y"]
        else:
            return None

    def gcj02_to_wgs84(self, lng, lat):
        url = "http://api.map.baidu.com/geoconv/v1/?coords={},{}&from=3&to=1&ak={}".format(lng, lat, self.ak)
        response = requests.get(url)
        data = json.loads(response.text)
        if data["status"] == 0:
            return data["result"][0]["x"], data["result"][0]["y"]
        else:
            return None

In the above code, the ak parameter is the key of Baidu Map API, which can be applied on the Baidu Map Open Platform.

Below, we can create a BaiduMap object and call its corresponding method for coordinate conversion. The sample code is as follows:

# 实例化BaiduMap对象
map_api = BaiduMap("Your_Key")

# WGS84坐标转百度坐标（GCJ-02）
lng = 116.404
lat = 39.915
bd_lng, bd_lat = map_api.wgs84_to_bd09(lng, lat)
print("WGS84 to BD-09: {}, {}".format(bd_lng, bd_lat))

# 百度坐标（BD-09）转WGS84坐标
bd_lng = 116.404
bd_lat = 39.915
lng, lat = map_api.bd09_to_wgs84(bd_lng, bd_lat)
print("BD-09 to WGS84: {}, {}".format(lng, lat))

# WGS84坐标转火星坐标（GCJ-02）
lng = 116.404
lat = 39.915
gcj_lng, gcj_lat = map_api.wgs84_to_gcj02(lng, lat)
print("WGS84 to GCJ-02: {}, {}".format(gcj_lng, gcj_lat))

# 火星坐标（GCJ-02）转WGS84坐标
gcj_lng = 116.404
gcj_lat = 39.915
lng, lat = map_api.gcj02_to_wgs84(gcj_lng, gcj_lat)
print("GCJ-02 to WGS84: {}, {}".format(lng, lat))

"Your_Key" in the above code needs to be replaced with your own Baidu Map API key.

4. Summary
Through the above sample code, we can see that through Python programming, we can easily use Baidu Map API to implement coordinate conversion function. Such functions are very useful in practical applications, such as navigation software, travel applications, and geographic information analysis. I hope this article will help you understand and use the coordinate conversion function in Baidu Map API documentation.

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