Regular expression to find precise pdf links in a webpage - regex

Question

Given url='http://normanpd.normanok.gov/content/daily-activity', the website has three types of arrests, incidents, and case summaries. I was asked to use regular expressions to discover the URL strings of all the Incidents pdf documents in Python.
The pdfs are to be downloaded in a defined location.
I have gone through the link and found that Incident pdf files URLs are in the form of:
normanpd.normanok.gov/filebrowser_download/657/2017-02-19%20Daily%20Incident%20Summary.pdf
I have written code :
import urllib.request
url="http://normanpd.normanok.gov/content/daily-activity"
response = urllib.request.urlopen(url)
data = response.read() # a `bytes` object
text = data.decode('utf-8')
urls=re.findall(r'(\w|/|-/%)+\sIncident\s(%|\w)+\.pdf$',text)
But in the URLs list, the values are empty.
I am a beginner in python3 and regex commands. Can anyone help me?

Answer 1

This is not an advisable method. Instead, use an HTML parsing library like bs4 (BeautifulSoup) to find the links and then only regex to filter the results.
from urllib.request import urlopen
from bs4 import BeautifulSoup
import re
url="http://normanpd.normanok.gov/content/daily-activity"
response = urlopen(url).read()
soup= BeautifulSoup(response, "html.parser")
links = soup.find_all('a', href=re.compile(r'(Incident%20Summary\.pdf)'))
for el in links:
print("http://normanpd.normanok.gov" + el['href'])
Output :
http://normanpd.normanok.gov/filebrowser_download/657/2017-02-23%20Daily%20Incident%20Summary.pdf
http://normanpd.normanok.gov/filebrowser_download/657/2017-02-22%20Daily%20Incident%20Summary.pdf
http://normanpd.normanok.gov/filebrowser_download/657/2017-02-21%20Daily%20Incident%20Summary.pdf
http://normanpd.normanok.gov/filebrowser_download/657/2017-02-20%20Daily%20Incident%20Summary.pdf
http://normanpd.normanok.gov/filebrowser_download/657/2017-02-19%20Daily%20Incident%20Summary.pdf
http://normanpd.normanok.gov/filebrowser_download/657/2017-02-18%20Daily%20Incident%20Summary.pdf
http://normanpd.normanok.gov/filebrowser_download/657/2017-02-17%20Daily%20Incident%20Summary.pdf
But if you were asked to use only regexes, then try something simpler:
import urllib.request
import re
url="http://normanpd.normanok.gov/content/daily-activity"
response = urllib.request.urlopen(url)
data = response.read() # a `bytes` object
text = data.decode('utf-8')
urls=re.findall(r'(filebrowser_download.+?Daily%20Incident.+?\.pdf)',text)
print(urls)
for link in urls:
print("http://normanpd.normanok.gov/" + link)

Answer 2

Using BeautifulSoup this is an easy way:
soup = BeautifulSoup(open_page, 'html.parser')
links = []
for link in soup.find_all('a'):
current = link.get('href')
if current.endswith('pdf') and "Incident" in current:
links.append('{0}{1}'.format(url,current))