Python---re

'''help----re'''
import re
string1='100 NORTH BROAD MAIN ROAD. 100'
print(string1.replace('ROAD.', 'RD.'))
print(re.sub('ROAD$', 'RD.', string1))
print(re.sub('^100', '200', string1))
'''
$ means endwith, 
^ means startwith
\\b means complete word
r means don't translate for \
'''
string2='100 ROAD BROAD.'
print(re.sub('\\bROAD', 'RD.', string2))
print(re.sub(r'\bROAD', 'RD.', string2))
print(re.sub(r'\bROAD', 'RD.', string2))
string3 ='Monday is My  day M'
print(re.search('^M?M?M', string3))
string5='MM'
print(re.search('^M?M?$', string5))
'''^ and $ means no symbol is before than M and no symbol is after M, it is critical'''
string4='LonDay is'
print(re.search('(^M|^L)?i?(s|k)', string4))
'''can not use ^(M|L)'''
print(re.search('^M{0,3}$', 'MMM'))
pattern1='''
^        #it means start with M
M        #the first pattern character
{0,3}    #the scope ,min is 0 ,max is 3
$        #then end of pattern, end with M
'''
print(re.search(pattern1, 'MMM', re.VERBOSE))

pattern2=re.compile(r'(\d{3})')
print(pattern2.search('422').groups())
'''pay attention: can not miss () of (\d{3})'''
pattern3=re.compile(r'^(\d{3})-(\d{3})-(\d*)-(\d+)-(\D+)$')
print(pattern3.search('301-555--122-s').groups())
'''* means 0 or more, + means 1 or more, D means not decimal ,d means decimal'''
print(re.sub('$', 'es', 'box'))
print(re.sub('[abc]','A', 'america'))
'''[] means select one of them, sub() means replace'''
print(re.sub('[^abc]', 'A', 'america'))
'''^ in [] means , except'''
print(re.findall('[0-9]', '1 is my favorite number from 0 to 100'))