Hey guys, Hope you all are doing great.
I have always found Regular expressions or REGEX quite amazing. You can solve your string related problem in just some simple magic of patterns.
Our brain works very well to identify the pattern in our day to day life. As these are visual clues, we tend to catch and analyse them better. In fact, their you make negligible mistake to tackle the scenario.
Say you have a pattern with concentric cirles:
Now you see that it has got a pattern in here, the small
circle grows by some radius say x and we have another circle and
so on...
This can be generalized in mathematical way, as in geometry is:
x + y + 2gx + 2fy + c' = 0
This same thing applies to string patterns or character arrays.
For Python we have a Regex module called re
Below are few function which you will find useful is many applications
I have always found Regular expressions or REGEX quite amazing. You can solve your string related problem in just some simple magic of patterns.
Our brain works very well to identify the pattern in our day to day life. As these are visual clues, we tend to catch and analyse them better. In fact, their you make negligible mistake to tackle the scenario.
Say you have a pattern with concentric cirles:
This can be generalized in mathematical way, as in geometry is:
x + y + 2gx + 2fy + c' = 0
This same thing applies to string patterns or character arrays.
For Python we have a Regex module called re
Below are few function which you will find useful is many applications
| Syntax | Definition | Examples |
| re.search(regex,str) | return match object if found, else None | pika = re.search(r"\w+@\w+\.com", "from pikachu@pokemon.com address") if pika : print "yes" print pika.group() # → pika@pika.com else: print "no"
|
| re.match(regex,str) | similar to re.search(), but match starts at beginning of string. | goku = re.match('ha','kamehameha') # succeed if goku == None: print "no match" else: print "yes match"
|
| re.split(regex,str) | return a list. | print re.split(r' +', 'Clark Kent is Superman')' # output: ['Clark', 'Kent', 'is', 'Superman'] print re.split(r'( +)(@+)', 'what @@do @@you @@think') # output: ['what', ' ', '@@', 'do', ' ', '@@', 'you', ' ', '@@', 'think'] print re.split(r' ', 'a b c d e', maxsplit = 2) # output: ['a', 'b', 'c d e']
|
| re.findall(regex,str) | return a list of non-overlapping (repeated) matches. | print re.findall(r'( +)(@+)', 'what @@@do @@you @think') # output: [(' ', '@@@'), (' ', '@@'), (' ', '@')]
|
| re.finditer(…) | similar to re.findall(), but returns a iterator. | for matched in re.finditer(r'(\w+)', 'where are the avengers'): print matched.group() # prints each word in a line
|
| re.sub(regex,replacement,str) | does replacement. Returns the new string. | def ff(pika): if pika.group(0) == "bulba": return "vena" elif pika.group(0) == "mender": return "izard" else: return pika.group(0) print re.sub(r"[aeiou]+", ff, "bulbasaur") # venasaur print re.sub(r"[aeiou]+", ff, "charmender") # charizard print re.sub(r"[aeiou]+", ff, "geek") # geek
|
| re.subn(…) | similar to re.sub(), but returns a tuple. 1st element is the new string, 2nd is number of replacement. | re.subn('\w+', 'Try', 'Cry Cry, Cry and Cry Again!', count=3) # ('Try Try, Try and Try Again!', 3) |
| re.escape(str) | add backslash to string for feeding it to regex as pattern. Return the new string. | re.escape('Lets meet spider man?') # output: Lets\\ meet\\ spider\\ man\\? |
To form a regular expression, it needs a bit or creativity
and foresightedness of the outcome.
For sure you need to know the regex symbols and rules to do
that, and all should be dancing in your mind to create an
efficient and effective pattern. To help you out, below is
the Python Regex Jump-starter:
Python Regex
Jump-starter:
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Please let me know your feedback, on how i can improve
and make it better. Till then!! Cheers!!
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