RegexLesson.py

"""
The regular expressions operations (re) module is a standard Python
library.  It is a beautiful collection of operations for finding and manipulating 
matched text.  

This program uses the re library to search the text in a file, regex.txt, or a string, text, for 
email addresses and phone numbers.  It copies the emails and phone numbers it finds
to a list called matches and prints them out neatly in a standard format.

You use the saved file as the text source or has a string called text.   Just use adjust triple
quotes commented out (sort of) the line(s) you don't want to use. 
the regex.txt file.

The program is a modification of a program found at 
https://automatetheboringstuff.com/chapter7/

See also the documentation at Python.org for the re library
(regular expression operations) here https://docs.python.org/3/library/re.html

"""

import re # The built-in regular expression module
import os # The built-in os module provides a standard interface to work with your native os. 


""" 
with open('regex.txt') as f1:
    text=f1.read()
 
Here is some text that can be used for demonstration purposes instead of 
reading a text file from the local current working directory.
"""
text =  'This text file contains a few emails addresses and phone numbers.\n\
Alex phone is home number is 813-123-4567.\n\
He has two email addresses aambrioso@hccfl.edu and alexambrioso@gmail.com.\n\
Gregory has two phone nunbers:  (cell) (813) 685-1234 and work 253-7000 ext. 1234.\n\
His email address in Greg.Johnson@yahoo.com.'


# Create a regex for matching emails.
emailRegex = re.compile(r"""(
    [a-zA-Z0-9._%+-]+      # username
     @                      # @ symbol
    [a-zA-Z0-9.-]+         # domain name
    (\.[a-zA-Z]{2,4})      # dot-something
    )""", re.VERBOSE)
    
# Create a regex for matching phone numbers and identify 
# the parts of a phone number.
phoneRegex = re.compile(r"""(
    (\d{3}|\(\d{3}\))?                # area code
    (\s|-|\.)?                        # separator
    (\d{3})                           # first 3 digits
    (\s|-|\.)                         # separator
    (\d{4})                           # last 4 digits
    (\s*(ext|x|ext.)\s*(\d{2,5}))?    # extension
    )""", re.VERBOSE)
    
# Any text in the file which has a typical email or phone number will be added to the list matches.
matches = []
for groups in phoneRegex.findall(text):
    # This code reformats the phone number in a standard way by using
    # the blocks identified when the number was matched to the regex.

    # Use the print statement to show the groups created by the regex expression.
    # print(f'{groups[1]=}, {groups[3]=}, {groups[5]=}')
    if groups[1] != '':
        phoneNum = '-'.join([groups[1], groups[3], groups[5]])
    else:
        phoneNum = '-'.join([groups[3], groups[5]])


    if groups[8] != '':
        phoneNum += ' x' + groups[8]
    matches.append(phoneNum)
for groups in emailRegex.findall(text):
       matches.append(groups[0])
    
# Neatly prints out emails and phone numbers found 
# in the regex.txt file.
n = 25
print('********** Text File **********')
print(text)
print('********** Phone numbers and Emails **********')
if len(matches) > 0:
    print('\n'.join(matches))
else:
    print('\nNo phone numbers or email addresses found.')
print(n * '*')