python_reference/reg_expr_2_operators.py
2013-11-30 21:08:54 -05:00

128 lines
3.1 KiB
Python

# 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
'''