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# Examples for using Python's Regular expression module "re"

# sr 11/30/2013

import re

'''OVERVIEW

'*' matches all characters that follow (0 or more)

'+' matches all characters that follow (1 or more)

'?' makes the previous character optional

'{4}' previous character must match exactly 4 times

'{2-4}' previous character must match exactly 2-4 times

'[0-9]' matches all characters in the set of numbers 0 to 9

'[A-Z]' matches all characters in the set of A to Z

'\d' matches all digits, e.g., '4', '9' ...

'\D' matches all NON-digit characters

'\s' matches all space characters: '', '\t', '\r', '\n'

'\S' matches all NON-space characters

'\w' matches all non-punctuation characters (i.e., letters and digits)

'\W' matches all NON-letter and NON-digit characters

'^bla' NOT-matches 'bla'

'let$' matches 'let' but not 'letter'

'\b' matches transition between non-word characters and word characters

'''

data = '''2013-01-01

2012-02-02

aaaa-02-02

aa-02-02

-04-04

2000 02-02

ghi stu

2012-03-03'''.strip().split('\n')

# A >> '*' matches all characters that follow (0 or more)

print (50*'-' + '\nA\n' + 50*'-')

for line in data:

match = re.search('(.*)-(..)-(..)', line) # note the parantheses

if match:

print(match.group(1), match.group(2), match.group(3))

'''

--------------------------------------------------

A

--------------------------------------------------

2013 01 01

2012 02 02

aaaa 02 02

aa 02 02

04 04

2012 03 03

'''

# B >> '+' matches all characters that follow (1 or more)

print (50*'-' + '\nB\n' + 50*'-')

for line in data:

match = re.search('(.+)-(..)-(..)', line) # note the parantheses

if match:

print(match.group(1), match.group(2), match.group(3))

'''

--------------------------------------------------

B

--------------------------------------------------

2013 01 01

2012 02 02

aaaa 02 02

aa 02 02

2012 03 03

'''

# C >> '?' makes the previous character optional

print (50*'-' + '\nC\n' + 50*'-')

for line in data:

match = re.search('(.+)-?(..)-(..)', line) # note the parantheses

if match:

print(match.group(1), match.group(2), match.group(3))

'''

--------------------------------------------------

C

--------------------------------------------------

2013- 01 01

2012- 02 02

aaaa- 02 02

aa- 02 02

- 04 04

2000 02 02

2012- 03 03

'''

# D >> '{4}' previous character must match exactly 4 times

print (50*'-' + '\nD\n' + 50*'-')

for line in data:

match = re.search('(a{4})-(..)-(..)', line) # note the parantheses

if match:

print(match.group(1), match.group(2), match.group(3))

'''

--------------------------------------------------

D

--------------------------------------------------

aaaa 02 02

'''

# E >>'{2-4}' previous character must match exactly 2-4 times

print (50*'-' + '\nE\n' + 50*'-')

for line in data:

match = re.search('(a{2,4})-(..)-(..)', line) # note the parantheses

if match:

print(match.group(1), match.group(2), match.group(3))

'''

--------------------------------------------------

E

--------------------------------------------------

aaaa 02 02

aa 02 02

'''