learn web scraping with python code example

Example 1: web scraping with python

# example of web scraping links using asyncio and using all cores
import asyncio, requests, aiohttp, os
from concurrent.futures import ThreadPoolExecutor, ProcessPoolExecutor, as_completed
from bs4 import BeautifulSoup as BS

executor = ThreadPoolExecutor(max_workers=8)
loop = asyncio.get_event_loop()

async def make_requests():
    urls = ['http://www.filedropper.com/lister.php?id=0', 'http://www.filedropper.com/lister.php?id=1', 'http://www.filedropper.com/lister.php?id=2', 'http://www.filedropper.com/lister.php?id=3', 'http://www.filedropper.com/lister.php?id=4', 'http://www.filedropper.com/lister.php?id=5', 'http://www.filedropper.com/lister.php?id=6', 'http://www.filedropper.com/lister.php?id=7', 'http://www.filedropper.com/lister.php?id=8', 'http://www.filedropper.com/lister.php?id=9', 'http://www.filedropper.com/lister.php?id=a', 'http://www.filedropper.com/lister.php?id=b', 'http://www.filedropper.com/lister.php?id=c', 'http://www.filedropper.com/lister.php?id=d', 'http://www.filedropper.com/lister.php?id=e', 'http://www.filedropper.com/lister.php?id=f', 'http://www.filedropper.com/lister.php?id=g', 'http://www.filedropper.com/lister.php?id=h', 'http://www.filedropper.com/lister.php?id=i', 'http://www.filedropper.com/lister.php?id=j', 'http://www.filedropper.com/lister.php?id=k', 'http://www.filedropper.com/lister.php?id=l', 'http://www.filedropper.com/lister.php?id=m', 'http://www.filedropper.com/lister.php?id=n', 'http://www.filedropper.com/lister.php?id=o', 'http://www.filedropper.com/lister.php?id=p', 'http://www.filedropper.com/lister.php?id=q', 'http://www.filedropper.com/lister.php?id=r', 'http://www.filedropper.com/lister.php?id=s', 'http://www.filedropper.com/lister.php?id=t', 'http://www.filedropper.com/lister.php?id=u', 'http://www.filedropper.com/lister.php?id=v', 'http://www.filedropper.com/lister.php?id=w', 'http://www.filedropper.com/lister.php?id=x', 'http://www.filedropper.com/lister.php?id=y', 'http://www.filedropper.com/lister.php?id=z']

    futures = [loop.run_in_executor(executor, requests.get, url) for url in urls]
    await asyncio.wait(futures)

    for future in futures:
        soup = BS(future.result().content)
        for all_links in soup.find_all('a', href=True):
            print("URL:", all_links['href'])    
            with open('filedropper_com.txt', 'a') as f:
                f.write(all_links['href'] + '\n')

loop.run_until_complete(make_requests())

Example 2: web scraper python

>>> from bs4 import BeautifulSoup
>>> raw_html = open('contrived.html').read()
>>> html = BeautifulSoup(raw_html, 'html.parser')
>>> for p in html.select('p'):
...     if p['id'] == 'walrus':
...         print(p.text)

'I am the walrus'

Example 3: web scraper python

def get_names():
    """
    Downloads the page where the list of mathematicians is found
    and returns a list of strings, one per mathematician
    """
    url = 'http://www.fabpedigree.com/james/mathmen.htm'
    response = simple_get(url)

    if response is not None:
        html = BeautifulSoup(response, 'html.parser')
        names = set()
        for li in html.select('li'):
            for name in li.text.split('\n'):
                if len(name) > 0:
                    names.add(name.strip())
        return list(names)

    # Raise an exception if we failed to get any data from the url
    raise Exception('Error retrieving contents at {}'.format(url))