CODEWITHSUNDEEP
pythonwildcard
Aaron Shea
Aaron Shea

Reputation: 123

Python wildcard matching

I have a python script that takes input using a pattern like this: 1** then takes multiple inputs after that like 100, 110, 011 ect. I need to test to see if the imputed data matches the pattern, the * can stand for either a 1 or a 0. What is the best way to go about doing this? I'm fairly new to Python, so explanations would be helpful.

Update: added input and output example

Example of correct input and output:

input: **1 (pattern) 001, 101, 000 output: 001, 101

Upvotes: 4

Views: 5541

Answers (3)

Brigand
Brigand

Reputation: 86220

I'd use zip instead of Regular Expressions. It lines up all of the elements of both strings and lets you loop through each pair.

def verify(pat, inp):
  for n,h in zip(pat, inp):
      if n == '*':
          if h not in ('0', '1'):
            return False
      elif h not in ('0', '1'):
          return False
      elif n != h:
          return False
  return True

# Example use:
>>> verify('**1', '001')
True
>>> verify('**1', '101')
True
>>> verify('**1', '000')
False

A shorter way of doing it by @DSM.

def verify(n, h):
    return all(c0 == c1 or (c0 == '*' and c1 in '01') for c0, c1 in zip(n, h))

# or even shorter
verify = lambda n,h:  all(c0 == c1 or (c0 == '*' and c1 in '01') for c0, c1 in zip(n, h))

Upvotes: 1

senderle
senderle

Reputation: 150987

I would suggest using the input string and replace to generate a simple regular expression:

>>> '1**0*'.replace('*', '[01]')
'1[01][01]0[01]'

Now that can be used in whatever way you want:

>>> import re
>>> pattern = '1**0*'.replace('*', '[01]')
>>> bool(re.match(pattern, '00000'))
False
>>> bool(re.match(pattern, '10000'))
True

If you aren't familiar with regular expressions, you might want to read a tutorial or two. But the fundamental idea is that any one of the characters between brackets is allowed. So a [01] matches either a 1 or a 0, as you requested in your question.

Upvotes: 3

Jörg Beyer
Jörg Beyer

Reputation: 3671

regex can match the input you described:

import re
yourinput = "100";
matchObj = re.match( r'(1..', yourinput)

the dot is probably what you described with your star.

there are lots of tutorial, that e.g. describe what you can do with a matchobject, look here http://www.tutorialspoint.com/python/python_reg_expressions.htm for a tutorial or here for the library documentation http://docs.python.org/library/re.html

Upvotes: 0

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