CODEWITHSUNDEEP
pythonbeautifulsoupweb-crawler
Abhishek Gangwar
Abhishek Gangwar

Reputation: 1767

difficulty in crawling anchor tags from html using beautifulsoup in python3

I am trying to extract the href's from the web page of an institution. I have to extract the dept codes for further crawling activity. and I have written following code:

import requests
import re
import urllib
from bs4 import BeautifulSoup

codesurl="http://www.iitkgp.ac.in/academics/?page=acadunits"
response = requests.get(codesurl)
# print(response.content)
soup=BeautifulSoup(response.content)
# print(soup.prettify())
p = re.compile('page=acadunits*')
p1 = re.compile('<a href=.*page=acadunits*')

links=soup.find_all("a")
print(links)
for link in links:
    # if p1.match(link):
        print("%s" %(link))

But I am not getting all the href's for example :

<a href="?page=acadunits&amp;&amp;dept=ME">Mechanical Engineering</a>
<a href="?page=acadunits&amp;&amp;dept=MD">Medical Science &amp; Technology</a>
<a href="?page=acadunits&amp;&amp;dept=MT">Metallurgical &amp; Materials Engineering</a>

and many more Can somebody help me with this.This is first time I am crawling. you can also look at the website.I need to extract dept code from url

dept=ME
dept=MT
dept=MD

My web page contains:

    <div class="tab_container">
<div id="tab1" class="tab_content" style="display: block;">
<h3></h3>
    <!--Content-->
    <img src="./Indian Institute of Technology Kharagpur_files/academicunits.jpg">
    <br><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=AE">Aerospace Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=AG">Agricultural &amp; Food Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=AR">Architecture &amp; Regional Planning</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=BT">Biotechnology</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=CH">Chemical Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=CM">Chemistry</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=CE">Civil Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=CS">Computer Science &amp; Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=CR">Cryogenic Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=ED">Center for Educational Technology</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=EE">Electrical Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=EC"> Electronics &amp; Electrical Communication Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=GS">G S Sanyal School of Telecommunications</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=MG">Geology &amp; Geophysics</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=HS">Humanities &amp; Social Sciences</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=IM">Industrial &amp; Systems Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=IT">Information Technology</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=MS">Materials Science</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=MM">Mathematics</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=ME">Mechanical Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=MD">Medical Science &amp; Technology</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=MT">Metallurgical &amp; Materials Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=MI">Mining Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=NA">Ocean Engineering &amp; Naval Architecture</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=N2">Oceans, Rivers, Atmosphere and Land Sciences</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=MP">Physics</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=PK">P K Sinha Centre for Bio Energy</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=RJ">Rajendra Mishra School of Engineering Entrepreneurship</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=RG">Rajiv Gandhi School of Intellectual Property Law</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=ID">Ranbir and Chitra Gupta School of Infrastructure Design and Management</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=RE">Reliability Engineering Centre</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=RT">Rubber Technology Centre</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=RD">Rural Development Centre</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=BS">School of Bioscience</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=ES">School of Energy Science &amp; Engineering</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=EF">School of Environmental Science and Technology</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=NT">School of Nano-Science and Technology</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=WM">School of Water Resources</a><br>
        <a href="http://www.iitkgp.ac.in/academics/?page=acadunits&amp;&amp;dept=SM">Vinod Gupta School of Management</a><br>
    <br><br>

   <!--Content-->
    </div>

but when I do :

codesurl="http://www.iitkgp.ac.in/academics/?page=acadunits"
response = requests.get(codesurl)
soup=BeautifulSoup(response.text)

soup does not show these href's can someone suggest how to extract these href tags??

Upvotes: 0

Views: 143

Answers (2)

alecxe
alecxe

Reputation: 473813

First of all, the department links are loaded dynamically with a GET request to this URL.

Then, the idea would be to find all links where href attribute value is matching a specific pattern and then use this pattern to extract the department codes. Working code:

import re

import requests
from bs4 import BeautifulSoup

codesurl = "http://www.iitkgp.ac.in/academics/academic.php"
response = requests.get(codesurl)
soup = BeautifulSoup(response.content, "lxml")

pattern = re.compile(r"dept=([A-Z]+)")
links = soup.find_all("a", href=pattern)

for link in links:
    print(pattern.search(link["href"]).group(1))

Prints:

AE
AG
AR
...
NT
WM
SM

Upvotes: 1

Sede
Sede

Reputation: 61225

The best way to do this is using parse_qs from the urllib.parse module.

for link in links:
    qs = parse_qs(link.get('href'))
    print('dept', qs['dept'][0])

or using rpartition

for link in links:
    print(link.get('href').rpartition('&&')[-1])

Upvotes: 0

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