Validate user input of comma separated coordinates with regex-based pattern matching

user_8629294 0
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I have a problem where the user can input any number of (x,y) co-ordinates within parentheses. For example, User A can input (1,1) (1,2) (1,3)

User B : (1,1)
User C : (3,2) (5,5) (6,1)

I want a generic pattern matching to check if the input entered by the user is valid. Input is valid only if it follows the above format. That is, (x,y)\s(a,b)\s(c,d). I am new to regex matching and I tried like (\\(\d,\d\\)\s){1,}. This does not seem to work. Also, space should not be there after the last co-ordinate entry. Can someone help me how to get this?

Thanks in advance.

input python regex string
3 Answers

If you want to validate the whole input, I'd suggest the use of re.match.

>>> pattern = re.compile('(\(\d+,\d+\)\s*)+$')    
>>> def isValid(string):
...     return bool(pattern.match(string.strip()))
... 
>>> string = '(1,1) (1,2) (1,3)'
>>> isValid(string)
True

Either the whole string matches, or nothing matches. By default, re.match starts from the beginning, and will return a match object if the string is valid, or None otherwise. The bool result will be used to evaluate the truthiness of this expression.

Note that the whitespace character has been made optional to simplify the expression. if you want a strict matching, I recommend looking at DYZ' answer.

Regex Details

(        # capturing group 
    \(       # opening paren 
    \d+      # 1 or more digits
    ,        # comma
    \d+      
    \)       # closing paren
    \s*      # 0 or more whitespace chars
)+       # specify repeat 1 or more times
$        # end of string
user_49090870

I included support for multi-digit numbers, just in case:

pattern = r"(\(\d+,\d+\)\s)*\(\d+,\d+\)$"
re.match(pattern, "(1,1) (1,2) (1,3)")
#<_sre.SRE_Match object; span=(0, 17), match='(1,1) (1,2) (1,3)'>
re.match(pattern, "(1,1)")
#<_sre.SRE_Match object; span=(0, 5), match='(1,1)'>
re.match(pattern, "(1,1) (1,2) (1,3) ") # no match
re.match(pattern, "(1,1) (1,2)(1,3)") # no match
user_44929320

You can try this:

import re

s = "(1,1) (1,2) (1,3)"
if re.findall("(\(\d+,\d+\)\s)|(\(\d+,\d+\)$)", s):
   pass
user_73267380
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