import re
# Regex Cheat sheet : https://www.dataquest.io/blog/regex-cheatsheet/
# Regex python tester : https://pythex.org/
# re doc : https://docs.python.org/3/library/re.html
text = "i like train"
reg = r"[a-c]" #the group of char a to c
if re.match(reg, text): #Check if regex is correct
print(text)
else:
print("Not any match")import re
>>> m = re.search('(?<=abc)def', 'abcdef')
>>> m.group(0)
'def'import re
text = "test1, test2, test3"
regex = re.compile(r"test1")
# Returns range of first match
print(regex.match(text).span())
# Returns text with all matches replaces with other text
print(regex.sub("replace", text))
# Returns every match
print(regex.findall(text))
# OUT:
#
# (0, 5)
# replace, replace, replace
# ['test1', 'test2', 'test3']# Let's say you want to check for a phone number in a string
# Note: Remove indentation
import re
phone_num_regex = re.compile(r'\d\d\d-\d\d\d-\d\d\d\d')
mobile_string = 'My number is 415-555-4242' # Not real number
any_phone_numbers = phone_num_regex.search(mobile_string)
print(any_phone_numbers)
The r in front of the string means it's a raw string (/n, /t, etc doesn't work)
In regex, if we use \d, it will look for any digit in your string (0-9)
If we search for \d\d\d-\d\d\d-\d\d\d\d, it will look for anywhere in the
string where there is a digit, followed by a digit, followed by a digit, followed
by a hyphen, ...
You can also use it in an if statement to check if there is a match or not
between a regex and a string with 're.match(regex, string)'
# Recursive Python3 program to find if a given pattern is
# present in a text
def exactMatch(text, pat, text_index, pat_index):
if text_index == len(text) and pat_index != len(pat):
return 0
# Else If last character of pattern reaches
if pat_index == len(pat):
return 1
if text[text_index] == pat[pat_index]:
return exactMatch(text, pat, text_index+1, pat_index+1)
return 0
# This function returns true if 'text' contain 'pat'
def contains(text, pat, text_index, pat_index):
# If last character of text reaches
if text_index == len(text):
return 0
# If current characters of pat and text match
if text[text_index] == pat[pat_index]:
if exactMatch(text, pat, text_index, pat_index):
return 1
else:
return contains(text, pat, text_index+1, pat_index)
# If current characters of pat and tex don't match
return contains(text , pat, text_index+1, pat_index)
# Driver program to test the above function
print(contains("geeksforgeeks", "geeks", 0, 0))
print(contains("geeksforgeeks", "geeksquiz", 0, 0))
print(contains("geeksquizgeeksquiz", "quiz", 0, 0))
# This code is contributed by ankush_953.re.search(r'cake$', "Cake! Let's eat cake").group()
## The next search will return the NONE value, try it:
re.search(r'cake$', "Let's get some cake on our way home!").group()