When does Python use a dictionary?

Dictionary (Dictionary) is a mutable container model in Python. It is composed of a set of key (key) value (value) pairs. This structure type is usually also called a map, or an associative array. , also called a hash table. Each key-value is separated by ":", each group is separated by ",", and the entire dictionary is enclosed by "{}".

#Wherever key-value pairs are used, you can use a dictionary. Dictionaries can be used for headers in crawlers(recommended learning:Python video tutorial)

# coding:utf-8 import requests from bs4 import BeautifulSoup class SpiderProxy(object): #Python版本为2.7以上 headers = { "Host": "www.xicidaili.com", "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:47.0) Gecko/20100101 Firefox/47.0", "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", "Accept-Language": "en-US,en;q=0.5", "Accept-Encoding": "gzip, deflate", "Referer": "http://www.xicidaili.com/wt/1", } def __init__(self, session_url): self.req = requests.session() self.req.get(session_url) def get_pagesource(self, url): html = self.req.get(url, headers=self.headers) return html.content def get_all_proxy(self, url, n): data = [] for i in range(1, n): html = self.get_pagesource(url + str(i)) soup = BeautifulSoup(html, "lxml") table = soup.find('table', id="ip_list") for row in table.findAll("tr"): cells = row.findAll("td") tmp = [] for item in cells: tmp.append(item.find(text=True)) data.append(tmp[1:3]) return data session_url = 'http://www.xicidaili.com/wt/1' url = 'http://www.xicidaili.com/wt/' p = SpiderProxy(session_url) proxy_ip = p.get_all_proxy(url, 10) for item in proxy_ip: if item: print item

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