斷斷續續學了1年多python，最近總算感覺自己入門了，記錄下這幾天用requests和BeautifulSoup寫的爬蟲。
python的環境是anaconda+pycharm。
直接上程式碼

@requires_authorization
"""
    作者：西瓜不是我的
    日期：2017年12月26日
    功能：爬取全國每個城市各個監測點的AQI
    版本：v11.0
"""
import requests
from bs4 import BeautifulSoup
import csv

def get_city_area_aqi(url):
    '''
        獲取城市監測點aqi
    '''
 

    r = requests.get(url, timeout=20)
    soup = BeautifulSoup(r.text, 'lxml')
    area_name = soup.find_all('thead')  # len = 1
    area_final_name = area_name[0].find_all('th')  # len = 13
    area_aqi = soup.find_all('tbody')  # len = 1
    area_final_aqi = area_aqi[0].find_all('tr')  # len = 13
    # 各監測點名稱
 

    area_name_list = []
    # 最終目錄
    final_list = []
    # 為各監測點名稱列表賦初值
    for i in range(len(area_final_name)):
        area_name_list.append(area_final_name[i].text)
    # 將資訊寫入到最終目錄中
    for i in range(len(area_final_aqi)):
        final_aqi = area_final_aqi[i].text.strip()
        aqi = final_aqi.split('\n'
 
)
        for j in range(len(area_name_list)):
            final_list.append((area_name_list[j], aqi[j]))
    return final_list

def write_to_csv(final_list,city_name):
    '''
        將獲取到的city_aqi列表寫到csv檔案中
    '''
    with open('aqi.csv', 'a', encoding='utf-8', newline='') as f:
        writer = csv.writer(f)
        row = [city_name]
        # for迴圈用來寫csv檔案的資料行
        for i, name in enumerate(final_list):
            row.append(name[1])
            if (i + 1) % 11 == 0:
                writer.writerow(row)
                row = [city_name]

def get_all_city_name(url):
    '''
        獲取所有城市的中文名和英文名
    '''
    r = requests.get(url,timeout = 30)
    soup = BeautifulSoup(r.text, 'lxml')
    city_div = soup.find_all('div',{'class':'bottom'})[1]
    city_name_list = city_div.find_all('a')

    city_name = []
    for name in city_name_list:
        name_text = name.text
        name_pinyin = name['href'][1:]
        city_name.append((name_text,name_pinyin))
    return city_name



def main():
    url = 'http://www.pm25.in'
    all_city_list = get_all_city_name(url)
    #寫csv檔案的第一行，即標題行
    write_row = ['city','監測點','AQI','空氣質量','首要汙染物','PM2.5','PM10','CO','NO2','O3-1','O3-8','SO2']
    with open('aqi.csv', 'w', encoding='utf-8', newline='') as f:
        writer = csv.writer(f)
        writer.writerow(write_row)
    #先獲取所以城市的英文名，根據英文名找到對應的url，再獲得每個城市各監測點的aqi值，最後寫入到scv檔案中
    for i,city in enumerate(all_city_list):
        city_name = city[0]
        city_pinyin = city[1]
        url = 'http://www.pm25.in/' + city_pinyin
        city_list = get_city_area_aqi(url)
        write_to_csv(city_list,city_name)
        #只爬取10個城市
        if i == 10:
            break

if __name__=='__main__':
    main()

第一次用markdown，就寫這麼多。