Regular expressions and patterns

Question

He you can see simple script for email matching using RE

# Exercise: make a regular expression that will match an email
def test_email(your_pattern):
    pattern = re.compile(r"^(john|python-list|wha)")
    emails = ["john@example.com", "python-list@python.org", "wha.t.`1an?ug{}ly@email.com"]
    for email in emails:
        if not re.match(pattern, email):
            print "You failed to match %s" % (email)
        elif not your_pattern:
            print "Forgot to enter a pattern!"
        else:
            print "%s was found in the %s" %(str(pattern),email)
pattern = r"^(john|python-list|wha)" # Your pattern here!
test_email(pattern)

As you can see here patter has been mentioned twisely both as the local and global

variables. Eventually I've obtained results like
<_sre.SRE_Pattern object at 0x223dba0> was found in the john@example.com
<_sre.SRE_Pattern object at 0x223dba0> was found in the python-list@python.org
<_sre.SRE_Pattern object at 0x223dba0> was found in the wha.t.`1an?ug{}ly@email.

How it possible to show real found pattern in the relusts instead of string like Pattern_object?

Why if I define a pattern like the example below, no patterns are found?

pattern = re.compile(r"$(org|com)") # find strings which end on the 'com' or 'org'

Answer 1

You need to print the matched groups. You're now printing the search pattern object, which is not a match. You should store the match if it exists, and print that.

# Exercise: make a regular expression that will match an email
def test_email(your_pattern):
    pattern = re.compile(r"^(john|python-list|wha)")
    emails = ["john@example.com", "python-list@python.org", "wha.t.`1an?ug{}ly@email.com"]
    for email in emails:
        match = re.match(pattern, email)
        if not match:
            print "You failed to match %s" % (email)
        elif not your_pattern:
            print "Forgot to enter a pattern!"
        else:
            print "%s was found in the %s" %(match.groups(), email)
pattern = r"^(john|python-list|wha)" # Your pattern here!
test_email(pattern)

Also note that you're overwriting the pattern in the first line of your function. You might want to change that to:

def test_email(your_pattern):
    pattern = your_pattern # See here.
    emails = ["john@example.com", "python-list@python.org", "wha.t.`1an?ug{}ly@email.com"]
    for email in emails:
        match = re.match(pattern, email)
        if not match:
            print "You failed to match %s" % (email)
        elif not your_pattern:
            print "Forgot to enter a pattern!"
        else:
            print "%s was found in the %s" %(match.groups(), email)

Be aware that re.match will match from the beginning of the line, thus if you need to match from say, my email is john@example.com, you need to use re.search.

More information regarding the search() vs. match()

Demo:

>>> pattern = r"^(john|python-list|wha)" # Your pattern here!
>>> test_email(pattern)
('john',) was found in the john@example.com
('python-list',) was found in the python-list@python.org
('wha',) was found in the wha.t.`1an?ug{}ly@email.com
>>>