2017.07.04

Keywords

• re.findall
• re.find
• re.search
• csv
• lxml
• xpath
• BeautifulSoup4

Checkout

• re.findall, .*?

  import re
  re.findall('<img username=(.*?) class>', src_str, re.S) # re.S 可以包含换行符
  re.find('<img username=(.*?) class>', src_str, re.S) # find 匹配到第一个符合条件的就结束匹配
  re.search().group()/group(1)/group(2) # ？
  

• csv 文件的写入

  import csv
  with open('result.csv', 'w', encoding="UTF-8") as f:
  # 定义字典数据形式的表格字段格式写入对象：文件，字段名
  write = csv.DictWriter(f, fieldnames=['username', 'reply', 'time'])
  # 写入表头
  write.writeheader()
  # 写入行数据
  write.writerows(rows_dic)
  

• lxml 使用

  from lxml import html
  import requests
  html_source = requests.get('www.baidu.com').text
  selector_object = html.fromstring(html_source)
  # 提取文本
  content_list = selector_object.xpath('//ui/li[@class="active"]/text()')
  content_list = selector_object.xpath('//ui/li[starts-with(@class, "active")]/text()')  # starts-with
  content_list = selector_object.xpath('//ui/li[@class="active"]/text()')
  content = selector.xpath('//ui/li/string(.)')
  # 提取属性
  title = selector.xpath('//a/@title')
  

• BeautifuSoup4

  pip install beautifulsoup4
  from bs4 import BeautifuiSoup
  # BeautifulSoup()