The purpouse this repository is to maintain some python common regex examples
. - Any character except new line
\d - Digits [0-9]
\D - Not a digit [^0-9]
\w - Word character [a-zA-Z0-9_]
\W - Not a word character [^a-zA-Z0-9_]
\s - Whitespace (space, tab, newline) [\t\n\r\f\v]
\S - Not whitespace (space, tab, newline) [^ \t\n\r\f\v]
Anchors doesn't match any characters, but identify some positions like new lines, before or after a space, starts with or ends with, these special characters are word boundaries characters
\b - Word boundary (indicated for white space or non alphanumeric character like new lines)
\B - Not a word boundary
^ - Beginning of a string
$ - End of a string
[] - Matches characters in brackets (characters into [] will match only 1 character in the set,special character into set does not need to be scaped)
[^ ] - Matches characters NOT in
| - Either Or
( ) - Group
* - 0 or more
+ - 1 or more
? - 0 or one
{3} - Exact number
{3,4} - Range of numbers (Minimum, Maximum)
pattern = re.compile(r'my_custom_pattern')
# Match pattern only at the beginning of the string.
pattern.match('text_to_search')
# Scan through a string, looking for any location where pattern matches. (return only the first match.)
pattern.search('text_to_search')
# Find all substrings where pattern matches and returns them as a list.
pattern.findall('text_to_search')
# Find all substrings where pattern matches and returns them as an iterator of match objects.
pattern.finditer('text_to_search')
# Find all substrings where pattern matches and replace them by given first parameter.
pattern.sub('new_content', 'text_to_search')match = pattern.match('my_custom_string'))
# Return the string matched in the group, if any group was give the default return will be the
# whole match "group(1)"
match.group(int: number = 1)
# Return the start position of the group.
match.start()
# Return the end position of the group.
match.end()
# Return a tuple containing the (start, end) positions of the match.
match.span()# pattern.match
def test_simple_match_method():
pattern = re.compile(r'string')
match = pattern.match('string, that it is')
assert match.group() == 'string'
assert match.span() == (0, 6)
assert match.start() == 0
assert match.end() == 6
def test_simple_match_method_does_not_match_in_the_middle_of_text():
pattern = re.compile(r'string')
match = pattern.match('that it is a string')
assert match is None
# pattern.search
def test_simple_search_method():
pattern = re.compile(r'string')
match = pattern.search('string, that it is')
assert match.group() == 'string'
assert match.span() == (0, 6)
assert match.start() == 0
assert match.end() == 6
def test_simple_search_method_does_match_in_the_middle_of_text():
pattern = re.compile(r'string')
match = pattern.search('that it is a string')
assert match.group() == 'string'
assert match.span() == (13, 19)
assert match.start() == 13
assert match.end() == 19
def test_simple_search_method_does_match_in_the_middle_of_text_just_one_time():
pattern = re.compile(r'string')
match = pattern.search('that it is a string, string it is')
assert match.group() == 'string'
assert match.span() == (13, 19)
assert match.start() == 13
assert match.end() == 19
# pattern.findall
def test_simple_findall_method_does_match_in_the_whole_text():
pattern = re.compile(r'string')
matches = pattern.findall('that it is a string, string it is')
assert matches == ['string', 'string']
def test_simple_findall_method_does_match_in_the_whole_text_not_found():
pattern = re.compile(r'string')
matches = pattern.findall('that it is a STRING, STRING it is')
assert matches == []
def test_simple_findall_method_does_match_in_the_whole_text_with_ignore_case_flag():
pattern = re.compile(r'string', re.IGNORECASE)
matches = pattern.findall('that it is a STRING, STRING it is')
assert matches == ['STRING', 'STRING']
## pattern.sub
def should_remove_all_special_characteres_with_re_sub_method():
content = '''
0 1 2 3 4 5 6 7 8 9 0 \n
a,b,c,d,e,f,g,h,i,j,k \t
0-1-2-3-4-5-6-7-8-9-0 \n
'''
pattern = re.compile(r'\s|[,-]') # it is equal to re.compile(r'\W')
cleaned_content = pattern.sub('', content)
print(cleaned_content)
assert cleaned_content == '01234567890abcdefghijk01234567890'
def should_remove_all_alphabetic_and_special_characteres_with_re_sub_method():
content = '''
0 1 2 3 4 5 6 7 8 9 0 \n
a,b,c,d,e,f,g,h,i,j,k \t
0-1-2-3-4-5-6-7-8-9-0 \n
'''
pattern = re.compile(r'\s|[a-zA-Z-,]') # it is equal to re.compile(r'\D')
cleaned_content = pattern.sub('', content)
print(cleaned_content)
assert cleaned_content == '0123456789001234567890'
def should_remove_all_numeric_and_special_characteres_with_re_sub_method():
content = '''
0 1 2 3 4 5 6 7 8 9 0 \n
a,b,c,d,e,f,g,h,i,j,k \t
0-1-2-3-4-5-6-7-8-9-0 \n
'''
pattern = re.compile(r'\s|[0-9-,]') # it is equal to re.compile(r'\d|[-,]')
cleaned_content = pattern.sub('', content)
print(cleaned_content)
assert cleaned_content == 'abcdefghijk'def test_should_match_phone_numbers():
"""
+55 (16) 1122-1213
+55 (16) 91122-1213
...
"""
content = read_file()
match_count = matcher(r'\+\d{2}\s\(\d{2}\)\s\d{4,5}[-.]\d{4}', content)
assert match_count == 100
def test_should_match_phone_numbers_ends_with_0_or_1():
"""
+55 (16) 1122-1210
+55 (16) 91122-1210
+55 (16) 1122-1211
+55 (16) 91122-1211
...
"""
content = read_file()
match_count = matcher(r'\+\d{2}\s\(\d{2}\)\s\d{4,5}[-.]\d{3}[01]', content)
assert match_count == 20
def test_should_match_all_prefix_with_regex_groups_more_readble():
content = '''
Mr. Schafer
Mr Smith
Ms Davis
Mrs. Robinson
Mr. T
'''
match_count = matcher(r'(Mr|Ms|Mrs)\.?\s[A-Z]\w*', content)
assert match_count == 5
def test_should_match_all_valid_emails():
content = '''
RafaelCassau@gmail.com
rafael.cassau@university.edu
rafael-cassau-89@my-work.net
rafael_cassau89@gmail.com.br
invalid-email1.com
invalid-email2@
invalid-email3@com
invalid-email4@gmail_2.com
'''
match_count = matcher(r'[a-zA-Z0-9-_+.]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+', content)
assert match_count == 4
def test_should_match_all_urls_with_re_group_and_findall_method():
content = '''
https://www.google.com
http://coreyms.com
https://youtube.com
https://www.nasa.gov
'''
pattern = re.compile(r'https?://(www\.)?(\w+)(\.\w+)')
matches = pattern.findall(content)
assert matches[0] == ('www.', 'google', '.com')
assert matches[1] == ('', 'coreyms', '.com')
assert matches[2] == ('', 'youtube', '.com')
assert matches[3] == ('www.', 'nasa', '.gov')
def test_should_replace_group_two_by_group_three_with_re_sub():
content = '''
https://www.google.com
http://coreyms.com
https://youtube.com
https://www.nasa.gov
'''
pattern = re.compile(r'https?://(www\.)?(\w+)(\.\w+)')
# replace group(2) "www." optional by group(3) "domain-name"
# the final string is without "http://" and "https://" prefix because this pattern
# is out of the group's scope
replaced_urls = pattern.sub(r'\2\3', content)
print(replaced_urls)
assert replaced_urls == '''
google.com
coreyms.com
youtube.com
nasa.gov
'''https://docs.python.org/3/howto/regex.html
https://youtu.be/K8L6KVGG-7o (Corey Schafer)