Day 06 流程控制和爬虫基础2

目录

• if 判断
  • 单分支结构
  • 双分支结构
  • 多分支结构
• for循环
  • for循环的基本用法
  • for循环嵌套
  • break
  • continue
• 爬虫基础2
  • 爬取豆瓣TOP250
  • 爬取豆瓣数据接口(异步数据)
  • 爬取电话号码(反爬破解基础)

if 判断

单分支结构

age = int(input('please enter your age: '))
if age > 18:
    print('adult aready')

双分支结构

age = int(input('please enter your age: '))
if age >= 18:
    print('adult aready')
else:
    print('just grow up')

多分支结构

age = int(input('please enter your age: '))
if age >= 18:
    print('adult aready')
elif age >= 13:
    print('teenager')
else:
    print('just grow up kid')

for循环

for循环的基本用法

# 把列表内部的值循环打印
for d in range(1, 32):
    print(f'{d}日')

for循环嵌套

# 内层循环全部走完，才会走一次外层循环，每次走入外层循环，内层循环都会重置
for m in range(1, 13):
    for d in range(1, 32):
        print(f'{m}月{d}日')

break

# 循环提前被中断
m = 2
 for d in range(1, 32):
        if d == 29:
            break
        print(f'{m}月{d}日')

continue

# 跳出本次循环，不执行下面的代码，然后直接进入下一次循环
for m in range(1, 13):
    for d in range(1, 32):
        if m == 2 and d > 28:
            continue
        print(f'{m}月{d}日')

爬虫基础2

爬取豆瓣TOP250

import requests
import re

# 获取所有电影的url
num = 0
for i in range(10):
    url = f'https://movie.douban.com/top250?start={num}&filter='
    num = num + 25

# 发送请求
    res = requests.get(url = url)
    data = res.text

# 解析数据
    movie_list = re.findall('<div class="item">.*?<a href="(.*?)">.*?<span class="title">(.*?)</span>.*?<span class="rating_num" property="v:average">(.*?)</span>', data, re.S)

# 保存数据
    with open('douban TOP250.txt', 'a', encoding='utf-8') as f:
        for line in movie_list:
            movie_name = line[1]
            movie_rating = line[2]
            movie_detail_web = line[0]
            movie_data = f'''
            电影名称: {movie_name}
            电影评分: {movie_rating}
            电影详情: {movie_detail_web}
            '''
            f.write(movie_data)

print('爬取成功,程序结束')

爬取豆瓣数据接口(异步数据)

import requests
import json

# 分析目标网址的异步请求返回的数据(接口)
# f12 -- network -- XHR -- headers -- Request URL

# 发送请求
num = 0
for i in range(10):
    url = f'https://movie.douban.com/j/chart/top_list?type=5&interval_id=100%3A90&action=&start={num}&limit=20'
    num = num + 20
    res  = requests.get(url = url)

# json 是一种第三方的数据格式
# json.dumps() 将python数据格式转换为json数据格式
# json.loads() 将json数据格式转化为python数据格式
    movie_list = json.loads(res.text)

# 保存数据
    for movie_dic in movie_list:
        movie_name = movie_dic['title']
        movie_rating = movie_dic['rating'][0]
        movie_rank = movie_dic['rank']
        movie_regions = movie_dic['regions']
        movie_release_date = movie_dic['release_date']
        movie_url = movie_dic['url']
        movie_data = f'''
        电影名称: {movie_name}
        电影评分: {movie_rating}
        电影排名: {movie_rank}
        拍摄国家: {movie_regions}
        电影年代: {movie_release_date}
        电影详情: {movie_url}
        '''
        with open('douban TOP 200 action movies', 'a', encoding='utf-8') as f:
            f.write(movie_data)

print('爬取成功,程序结束')

爬取电话号码(反爬破解基础)

import requests
import re

url='http://qiche.huangye88.com/xinxi/s121quumg56853.html'

# 反爬策略,通过User-Agent判断是否是浏览器
# f12 -- Network -- All -- Name第一行 -- Headers -- Request Headers -- User-Agent

headers = {'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36'}

# 发送请求
res = requests.get(url = url, headers = headers)
data = res.text

# 解析数据
phone_num_list= re.findall('<ul class="pro">.*?<li><label>手<span class="none">占</span>机</label><h3 class="big">(.*?)</h3></li>.*?</ul>',data, re.S)

# 输出数据
phone_num = phone_num_list[0]
print(phone_num)