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

For more Python related technical articles, please visit Python tutorial Column for learning!

The above is the detailed content of When does Python use a dictionary?. For more information, please follow other related articles on the PHP Chinese website!