Question

我必须编写一个程序来读取此链接中的HTML（http://python-data.dr-chuck.net/known_by_Maira.html），从锚标记中提取href =值，扫描相对于名字位于特定位置的标记在列表中，按照该链接重复该过程多次，并报告您找到的姓氏。

我应该在第18位找到链接（第一个名字是1），按照该链接重复此过程7次。答案是我检索的姓氏。

这是我找到的代码，它运行得很好。

import urllib

from BeautifulSoup import *

url = raw_input("Enter URL: ")
count = int(raw_input("Enter count: "))
position = int(raw_input("Enter position: "))

names = []

while count > 0:
    print "retrieving: {0}".format(url)
    page = urllib.urlopen(url)
    soup = BeautifulSoup(page)
    tag = soup('a')
    name = tag[position-1].string
    names.append(name)
    url = tag[position-1]['href']
    count -= 1

print names[-1]

我真的很感激，如果有人可以向我解释，就像你对一个10岁的孩子一样，在while循环中发生了什么。我是Python的新手，非常感谢指导。

非常感谢你提前

Answer 1

while count > 0:                         # because of `count -= 1` below,
                                         # will run loop count times

    print "retrieving: {0}".format(url)  # just prints out the next web page
                                         # you are going to get

    page = urllib.urlopen(url)           # urls reference web pages (well,
                                         # many types of web content but
                                         # we'll stick with web pages)

    soup = BeautifulSoup(page)           # web pages are frequently written
                                         # in html which can be messy. this
                                         # package "unmessifies" it

    tag = soup('a')                      # in html you can highlight text and
                                         # reference other web pages with <a>
                                         # tags. this get all of the <a> tags
                                         # in a list

    name = tag[position-1].string        # This gets the <a> tag at position-1
                                         # and then gets its text value

    names.append(name)                   # this puts that value in your own
                                         # list.

    url = tag[position-1]['href']        # html tags can have attributes. On
                                         # and <a> tag, the href="something"
                                         # attribute references another web
                                         # page. You store it in `url` so that
                                         # its the page you grab on the next
                                         # iteration of the loop.
    count -= 1

Answer 2

import urllib.request, urllib.parse, urllib.error
from bs4 import BeautifulSoup


total=0
url = input('Enter - ')
c=input('enter count-')
count=int(c)
p=input('enter position-')
pos=int(p)
while total<=count:
    html = urllib.request.urlopen(url, context=ctx).read()
    print("Retrieving",url)
    soup = BeautifulSoup(html, 'html.parser')
    tags = soup('a')
    counter=0
    for tag in tags:
        counter=counter+1
        if(counter<=pos):
            x=tag.get('href',None)
            url=x
        else:
            break
    total=total+1

Answer 3

您可以输入要从页面中检索的网址数

0）打印网址 1）打开网址 2）读取源 BeautifulSoup docs

3）获取每个a标签
4）得到整个<a ...></a>我认为 5）将其添加到列表names
6）从names的最后一项获取网址，即从href中提取<a ...></a> 7）打印列表的最后一个names

Answer 4

[答案：我应该在第18位找到链接（名字是1），跟随该链接并重复此过程7次。答案是]

以下链接在python中

4 个答案: