: : : 2017-11-29

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# matching string pattern1 = "cat" pattern2 = "bird" string = "dog runs to cat" print(pattern1 in string) # True print(pattern2 in string) # False

import re # regular expression pattern1 = "cat" pattern2 = "bird" string = "dog runs to cat" print(re.search(pattern1, string)) # <_sre.SRE_Match object; span=(12, 15), match='cat'> print(re.search(pattern2, string)) # None

# multiple patterns ("run" or "ran") ptn = r"r[au]n" # start with "r" means raw string print(re.search(ptn, "dog runs to cat")) # <_sre.SRE_Match object; span=(4, 7), match='run'>

print(re.search(r"r[A-Z]n", "dog runs to cat")) # None print(re.search(r"r[a-z]n", "dog runs to cat")) # <_sre.SRE_Match object; span=(4, 7), match='run'> print(re.search(r"r[0-9]n", "dog r2ns to cat")) # <_sre.SRE_Match object; span=(4, 7), match='r2n'> print(re.search(r"r[0-9a-z]n", "dog runs to cat")) # <_sre.SRE_Match object; span=(4, 7), match='run'>

# \d : decimal digit print(re.search(r"r\dn", "run r4n")) # <_sre.SRE_Match object; span=(4, 7), match='r4n'> # \D : any non-decimal digit print(re.search(r"r\Dn", "run r4n")) # <_sre.SRE_Match object; span=(0, 3), match='run'> # \s : any white space [\t\n\r\f\v] print(re.search(r"r\sn", "r\nn r4n")) # <_sre.SRE_Match object; span=(0, 3), match='r\nn'> # \S : opposite to \s, any non-white space print(re.search(r"r\Sn", "r\nn r4n")) # <_sre.SRE_Match object; span=(4, 7), match='r4n'> # \w : [a-zA-Z0-9_] print(re.search(r"r\wn", "r\nn r4n")) # <_sre.SRE_Match object; span=(4, 7), match='r4n'> # \W : opposite to \w print(re.search(r"r\Wn", "r\nn r4n")) # <_sre.SRE_Match object; span=(0, 3), match='r\nn'> # \b : empty string (only at the start or end of the word) print(re.search(r"\bruns\b", "dog runs to cat")) # <_sre.SRE_Match object; span=(4, 8), match='runs'> # \B : empty string (but not at the start or end of a word) print(re.search(r"\B runs \B", "dog runs to cat")) # <_sre.SRE_Match object; span=(8, 14), match=' runs '> # \\ : match \ print(re.search(r"runs\\", "runs\ to me")) # <_sre.SRE_Match object; span=(0, 5), match='runs\\'> # . : match anything (except \n) print(re.search(r"r.n", "r[ns to me")) # <_sre.SRE_Match object; span=(0, 3), match='r[n'> # ^ : match line beginning print(re.search(r"^dog", "dog runs to cat")) # <_sre.SRE_Match object; span=(0, 3), match='dog'> # $ : match line ending print(re.search(r"cat$", "dog runs to cat")) # <_sre.SRE_Match object; span=(12, 15), match='cat'> # ? : may or may not occur print(re.search(r"Mon(day)?", "Monday")) # <_sre.SRE_Match object; span=(0, 6), match='Monday'> print(re.search(r"Mon(day)?", "Mon")) # <_sre.SRE_Match object; span=(0, 3), match='Mon'>

string = """ dog runs to cat. I run to dog. """ print(re.search(r"^I", string)) # None print(re.search(r"^I", string, flags=re.M)) # <_sre.SRE_Match object; span=(18, 19), match='I'>

# * : occur 0 or more times print(re.search(r"ab*", "a")) # <_sre.SRE_Match object; span=(0, 1), match='a'> print(re.search(r"ab*", "abbbbb")) # <_sre.SRE_Match object; span=(0, 6), match='abbbbb'> # + : occur 1 or more times print(re.search(r"ab+", "a")) # None print(re.search(r"ab+", "abbbbb")) # <_sre.SRE_Match object; span=(0, 6), match='abbbbb'> # {n, m} : occur n to m times print(re.search(r"ab{2,10}", "a")) # None print(re.search(r"ab{2,10}", "abbbbb")) # <_sre.SRE_Match object; span=(0, 6), match='abbbbb'>

match = re.search(r"(\d+), Date: (.+)", "ID: 021523, Date: Feb/12/2017") print(match.group()) # 021523, Date: Feb/12/2017 print(match.group(1)) # 021523 print(match.group(2)) # Date: Feb/12/2017

match = re.search(r"(?P<id>\d+), Date: (?P<date>.+)", "ID: 021523, Date: Feb/12/2017") print(match.group('id')) # 021523 print(match.group('date')) # Date: Feb/12/2017

# findall print(re.findall(r"r[ua]n", "run ran ren")) # ['run', 'ran'] # | : or print(re.findall(r"(run|ran)", "run ran ren")) # ['run', 'ran']

print(re.sub(r"r[au]ns", "catches", "dog runs to cat")) # dog catches to cat

print(re.split(r"[,;\.]", "a;b,c.d;e")) # ['a', 'b', 'c', 'd', 'e']

compiled_re = re.compile(r"r[ua]n") print(compiled_re.search("dog ran to cat")) # <_sre.SRE_Match object; span=(4, 7), match='ran'>

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