Python的听课笔记案例8--空气污染指数计算8.0

上一节讨论了如何获取所有城市。AQI，只有获得者AQI输入，而不是保存，本课重点介绍如何获取AQI保存到本地CSV文件。

"""
    作者：lanxingbudui
    日期：2020-03-04
    功能：AQI计算
    版本：8.0
"""

import requests
from bs4 import BeautifulSoup
import csv

def get_city_aqi(city_pinyin):
    """
        得到一座城市的全部。AQI指标
    """
    url = http://pm25.in/ + city_pinyin
    r = requests.get(url, timeout=30)  # 链接Web请求
    # print(r.status_code)  # 打印返回结果，200成功 400失败
    soup = BeautifulSoup(r.text, lxml)  # 创建BeautifulSoup对象
    div_list = soup.find_all(div, {class: span1}) # 查找所有spen1属性的节点
    # 或者 = soup.find_all(div, class_ = spanl)  # 不建议这样做，因为class是一个关键字，有时容易忘记下划线。

    city_aqi = []
    for i in range(8):
        div_content = div_list[i]
        caption = div_content.find(div, {class: caption}).text.strip()
        value = div_content.find(div, {class: value}).text.strip()
        # .text是为了得到财产的价值，和。.strip()从上一步中删除 text 字符串末尾的空格或换行符。
        city_aqi.append( value)
    return city_aqi

def get_all_cities():
    """
        获取所有城市
    """
    url = http://pm25.in/
    city_list = []
    r = requests.get(url, timeout=30)  # 链接Web请求
    soup = BeautifulSoup(r.text, lxml)  # 创建BeautifulSoup对象
    city_div = soup.find_all(div, {class: bottom})[1]
    # 阿坝州 得到像这样的段落，把所有的城市都拿下。
    city_link_list = city_div.find_all(a)
    for city_link in city_link_list:
        city_name = city_link.text  # 获取value值---阿坝州
        city_pinyin = city_link[href][1:] # 获取hrdf的属性值 --/abazhou 并消去/
        city_list.append((city_name, city_pinyin))
    return city_list

def main():
    """
        主函数
    """
    city_list = get_all_cities()
    # for city in city_list:
    #     city_name = city[0]
    #     city_pinyin = city[1]
    #     city_aqi = get_city_aqi(city_pinyin)
    #     print(city_name, city_aqi)
    header = [City, AQI, PM2.5/1h, PM10/1h, CO/1h, NO2/1h, O3/1h, O3/8h, SO2/1h]
    with open(china_city_aqi.csv, w, encoding=utf-8, newline=) as f:
        writer = csv.writer(f)
        writer.writerow(header)
        for i, city in enumerate(city_list):
            if (i + 1) % 10 == 0:
                print(已处理{}数据，总计。{}条数据.format(i + 1, len(city_list)))
            city_name = city[0]
            city_pinyin = city[1]
            city_aqi = get_city_aqi(city_pinyin)
            row = [city_name] + city_aqi
            writer.writerow(row)

if __name__ == __main__:
    main()