python菜鸟知识

• 去除空格

str = ' 这是 含 空格 '
print(f'去除两端空格={str.strip()}')
print(f'去除左端空格={str.lstrip()}')
print(f'去除右端空格={str.rstrip()}')
print(f'去除全部空格={str.replace(" ", "")}')

• 方法返回对象yield

yield ':'.join([ip, port])yield {'ranking': ranking,'name': name,'img': img,'score': score,'author': author,'desc': desc,}

• 字符串格式化变量format

BASE_URL = 'https://proxylist.geonode.com/api/proxy-list?limit=500&page={page}&sort_by=lastChecked&sort_type=desc'MAX_PAGE = 18urls = [BASE_URL.format(page=page) for page in range(1, MAX_PAGE + 1)]

• 字符串拆分split

addr_split = addr.split(':')if(len(addr_split) == 2):host = addr_split[0]port = addr_split[1]yield Proxy(host=host, port=port)

• 字符串拼接

tmp = ['b', 'a', 'c']
print(",".join(str(i) for i in tmp))

• time格式化strptime

from datetime import datetimetargetTimeStr = "2024-10-08 10:08:00"
target_time = datetime.strptime(targetTimeStr, "%Y-%m-%d %H:%M:%S")# 获取当前时间current_time = datetime.now()print(f"当前时间: {current_time.strftime('%Y-%m-%d %H:%M:%S.%f')}")# 检查当前时间是否达到了目标时间if current_time >= target_time:

• json转对象 【json.loads】

result = json.loads(html)

• 对象转json 【json.dumps】

json.dumps(item, ensure_ascii=False)

• 对象中获取属性值

proxy_list = result['data']

• http请求并返回响应内容

import requests# 1 基础
def request_dangdang(url):try:response = requests.get(url)if response.status_code == 200:return response.textexcept requests.RequestException as e:print(e)return None# 2 扩展【设置header】
def request_data(url):headers = {'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36','cookie': 'bid=dT8Z3OE5_cY; _pk_id.100001.4cf6=97307cec25d927ab.1727414571.; __utmz=30149280.1727414571.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utmz=223695111.1727414571.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __yadk_uid=kz8b5hlKFkxH8Y9DITjOMuxWgBYikz0h; ll="108296"; _vwo_uuid_v2=D5055D26948C52E0832B26F1769798A7F|836a6dfe85637bb8c39462e0dadf8747; __utmc=30149280; __utmc=223695111; _pk_ses.100001.4cf6=1; ap_v=0,6.0; __utma=30149280.1074059804.1727414571.1728178377.1728193731.4; __utmb=30149280.0.10.1728193731; __utma=223695111.688962959.1727414571.1728178377.1728193731.4; __utmb=223695111.0.10.1728193731'}try:response = requests.get(url=url, headers=headers)if response.status_code == 200:return response.textreturn Noneexcept requests.RequestException:return None

• 文件写入txt

"""抓取到的数据写入文件"""def write_item_to_file(item):print('开始写入数据 ====> ' + str(item))with open('dangdang_top_500_book.txt', 'a', encoding='UTF-8') as f:f.write(json.dumps(item, ensure_ascii=False) + '\n')f.close()

• 写入Excel

import xlwt# 数据写入Excel
def save_to_excel(result_list):if result_list is None:returnbook = xlwt.Workbook(encoding='utf-8')sheet = book.add_sheet('豆瓣电影Top250', cell_overwrite_ok=True)sheet.write(0, 0, '排名')sheet.write(0, 1, '电影名称')sheet.write(0, 2, '图片')sheet.write(0, 3, '评分')sheet.write(0, 4, '作者')sheet.write(0, 5, '简介')for i, item in enumerate(result_list):row = i + 1sheet.write(row, 0, item['ranking'])sheet.write(row, 1, item['name'])sheet.write(row, 2, item['img'])sheet.write(row, 3, item['score'])sheet.write(row, 4, item['author'])sheet.write(row, 5, item['desc'])book.save('豆瓣电影Top250.xls')

• for循环

# 1-25页
if __name__ == '__main__':for i in range(1, 26):print(f'正在抓取第{i}页')main(i) #自己的业务处理函数

• html解析 BeautifulSoup

import requests
from bs4 import BeautifulSoup
import xlwt# 采集数据
def collect_data():result_list = []# 分页获取数据for i in range(0, 10):url = 'https://movie.douban.com/top250?start=' + str(i * 25) + '&filter='html = request_data(url)soup = BeautifulSoup(html, 'lxml')movie_sub_list = parse_result(soup)if movie_sub_list:result_list.extend(movie_sub_list)# print(f'movie_list={movie_list}')if result_list:save_to_excel(result_list)# 解析数据
def parse_result(soup):movie_list_this_page = soup.find('ol', class_='grid_view').find_all('li')for item in movie_list_this_page:ranking = item.find('em').get_text()name = item.find(class_='title').stringimg = item.find('a').find('img').get('src')score = item.find(class_='rating_num').stringauthor = item.find('p', class_='').get_text(strip=True)if item.find(class_='inq') is not None:desc = item.find(class_='inq').stringelse:desc = '暂无'print(ranking, name, img, score, author, desc)yield {'ranking': ranking,'name': name,'img': img,'score': score,'author': author,'desc': desc,}

• 进程池使用multiprocessing

import multiprocessingimport requests
from bs4 import BeautifulSoup
import xlwt
import time
import sys# 采集数据
def collect_data():result_list = []start_time = time.time()urls = []try:# 根据电脑核数设置进程数pool = multiprocessing.Pool(multiprocessing.cpu_count())# pool = multiprocessing.Pool(1)# 分页获取数据for i in range(0, 10):url = 'https://movie.douban.com/top250?start=' + str(i * 25) + '&filter='urls.append(url)# 各进程处理后格式为：[[{},{}],[{}]]result_list_mid = pool.map(collect_data_pool, urls)# result_list_mid = pool.apply_async(collect_data_pool, urls)print('总条数=======', len(result_list_mid))if result_list_mid:result_list = [item for sublist in result_list_mid for item in sublist]# result_list.sort(key=lambda x: x['ranking'], reverse=True)save_to_excel(result_list)pool.close()pool.join()except Exception as e:print('采集数据【异常】', str(e))end_time = time.time()print('总耗时：', end_time - start_time)

持续更新补充ing……