web scraping python book code example

Example 1: python web scraping

# basic web scraping with python
# Import libraries
import requests
import urllib.request
import time
from bs4 import BeautifulSoup

# Set the URL you want to webscrape from
url = 'http://web.mta.info/developers/turnstile.html'

# Connect to the URL
response = requests.get(url)

# Parse HTML and save to BeautifulSoup object¶
soup = BeautifulSoup(response.text, "html.parser")

# To download the whole data set, let's do a for loop through all a tags
line_count = 1 #variable to track what line you are on
for one_a_tag in soup.findAll('a'):  #'a' tags are for links
    if line_count >= 36: #code for text files starts at line 36
        link = one_a_tag['href']
        download_url = 'http://web.mta.info/developers/'+ link
        urllib.request.urlretrieve(download_url,'./'+link[link.find('/turnstile_')+1:]) 
        time.sleep(1) #pause the code for a sec
    #add 1 for next line
    line_count +=1

Example 2: 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))