Question

Use the Python “re” module to do the following:

1. Write a regular expression pattern that matches string “March 1, 2019, Mar 1, 2019, March First, 2019, March First, 19”. No credit for not using special characters: “*,+,?, | and etc” to do the matching.

2. Write a regular expression pattern that matches strings representing trains. A single letter stands for each kind of car in a train: Engine, Caboose, Boxcar, Passenger car, and Dining car. There are four rules specifying how to form trains.

1. One or more Engines appear at the front; one Caboose at the end.

2. Boxcars always come in pairs: BB, BBBB, etc.

3. There cannot be more than four Passenger cars in a series.

4. One Dining car must follow each series of passenger cars.

These cars cannot appear anywhere other than these locations.

Here are some legal and illegal examples.

EC Legal: the smallest train

EEEPPDBBPDBBBBC Legal : simple train showing all the cars

EEBB Illegal: no caboose (everything else OK)

EBBBC Illegal: three boxcars in a row

EEPPPPPDBBC Illegal: more than four passenger cars in a row

EEPPBBC Illegal: no dining car after passenger cars

EEBBDC Illegal: dining car after box car

What to turn in:

1. Your Python expressions or module.

2. Paste your test results.

Answer 1

1.

solution

code

output

#import the re module import re # regular expression regex" ([a-zA-2) d+)" matchdata= re.search (regex, "March 1, 2019, Mar 1, 2019, March First, 2019, March First, 19") if matchdata - None: !-None: # display the month print "string matches : %s" % (matchdata.group(1)) #does not match the regular expression string else: print "The regex pattern does not match."

string matches: March

copyable code

#import the re module

import re

# regular expression

regex = r"([a-zA-Z]+) (\d+)"

matchdata = re.search(regex, "March 1, 2019, Mar 1, 2019, March First, 2019, March First, 19")

if matchdata != None:

    

     # display the month

     print "string matches: %s" % (matchdata.group(1))

    

#does not match the regular expression string

else:

     print "The regex pattern does not match."

2.

coding

import re #check the valid train process def isValid Train (train1): patternl - r'E+ (((P PPI PPP PPPP) D) (BB))CS if re.match (patternl, traini): return True return False sprint the reult def check Print Train (trainl): print ("Train", traini, "is valid:", isValid Train (train1)) check Print Train ("EC") check Print Train ("EEEPPDBBPDBBBBC") check Print Train ("EEBB") check_Print_Train ("EBBBC") check Print Train ("EEPPPPPPDBBC") check_Print_Train ("EEPPBBC") check Print Train("EEBBDC")

output

RESTART: C:\Users\M.MANOGAR Desktop match.py 'Train','EC', 'is valid:', True) ('Train''EEEPPDBBPDBBBBC',is valid: ', True) ('Train', 'FEBB י , 'is valid:", False) ('Train', EBBBC','is valid:', False) 'Train',EEPPPPPDBBC','is valid:', False) ('Train''EEPPBBC','is valid:', False) ('Train EEBBDC, 'is valid: ', False)

copyable code

import re

#check the valid train process

def isValid_Train(train1):

    pattern1 = r'^E+(((P|PP|PPP|PPPP)D)*(BB)*)*C$'

    if re.match(pattern1, train1):

        return True

    return False

#print the reult

def check_Print_Train(train1):

    print("Train", train1, "is valid:", isValid_Train(train1))

check_Print_Train("EC")

check_Print_Train("EEEPPDBBPDBBBBC")

check_Print_Train("EEBB")

check_Print_Train("EBBBC")

check_Print_Train("EEPPPPPPDBBC")

check_Print_Train("EEPPBBC")

check_Print_Train("EEBBDC")