Home > Software design >  Why does this regex fail when trying to tell if there is a numeric character or more than one numeri
Why does this regex fail when trying to tell if there is a numeric character or more than one numeri

Time:10-03

import re

input_text = "hay alrededor de 4 coches el dia 7 del mes 5" #example 1
input_text = "Serian 4 unidades de mermelada para el dia 04 del 8 de este año 2023"  #example 2
input_text = "Hay 10 unidades para el dia 15 del 12 y seran 9 ya para el 7 de noviembre"  #example 3
input_text = "Hay 10 unidades para el 15 del 1º mes del año y seran alrededor de 9 para el 7º dia del mes de noviembre"  #example 4


#for days
standard_number_of_digits_re_1 = r"(?:del dia|de el dia|el dia|del|de el|el)[\s|]*(\b\d{1}\b)"
standard_number_of_digits_re_2 = r"(\b\d{1}\b)[\s|]*º[\s|]*dia"

re_1_and_re_2 = r"(?:"   standard_number_of_digits_re_1   r"|"   standard_number_of_digits_re_2    r")"

#for months
#standard_number_of_digits_re_3 = re_1_and_re_2   r"(?:del mes|de el mes|del|de el)[\s|]*(\b\d{1}\b)"
#standard_number_of_digits_re_4 = re_1_and_re_2   r"(?:del mes|de el mes|del|de el)[\s|]*(\b\d{1}\b)[\s|]*(?:º[\s|]*mes del año|º[\s|]*mes)"

standard_number_of_digits_re_3 = r"(?:del mes|de el mes|del|de el)[\s|]*(\b\d)"
standard_number_of_digits_re_4 = r"(?:del mes|de el mes|del|de el)[\s|]*(\b\d)[\s|]*(?:º[\s|]*mes del año|º[\s|]*mes)"


#replacement with this conditions, and put '0' in front a day number only if it is one number and not two(or more numbers)
#  example: '1' --> '01'  or  '10' --> '10'
input_text = re.sub(standard_number_of_digits_re_3, r"0\1", input_text)
input_text = re.sub(standard_number_of_digits_re_4, r"0\1", input_text)
input_text = re.sub(standard_number_of_digits_re_1, r"0\1", input_text)
input_text = re.sub(standard_number_of_digits_re_2, r"0\1", input_text)

print(repr(input_text)) #output

The problem I'm having is that the regex don't seem to work correctly since I can't do the replacements, but trying in several code editors I notice these 2 things:

  • In the Regex Debuger introducir la descripción de la imagen aquí

    • In the SublimeText editor, when I put an r in front of "(?:" the whole line is immediately put as if it were a string of characters although you can see how this string is separated with operators in the middle in charge of the concatenation, however in StackOverflow that line is displayed correctly.

    introducir la descripción de la imagen aquí

    I do not know if these observations are important in the malfunction of these regex, but for some reason that I cannot find, the regex cannot extract the text to be edited by placing (if applicable) a 0 in front.

    Leaving the output should be like this when printing them:

    "hay alrededor de 4 coches el dia 07 del mes 05" #for example 1
    "Serian 4 unidades de mermelada para el dia 04 del 08 de este año 2023"  #for example 2
    "Hay 10 unidades para el dia 15 del 12 y seran 9 ya para el 07 de noviembre"  #for example 3
    "Hay 10 unidades para el 15 del 01º mes del año y seran alrededor de 9 para el 07º dia del mes de noviembre"  #for example 4
    

    What modifications should I make to get these results? I think the problem is in this part of the regex (\b\d{1}\b)


    Edited code

    import re
    
    input_text = "hay alrededor de 4 coches el dia 7 del mes 5" #example 1
    #input_text = "Serian 4 unidades de mermelada para el dia 04 del 8 de este año 2023"  #example 2
    input_text = "Hay 10 unidades para el dia 15 del 12 y seran 9 ya para el 7 de noviembre"  #example 3
    #input_text = "Hay 10 unidades para el 15 del 1º mes del año y seran alrededor de 9 para el 7º dia del mes de noviembre"  #example 4
    
    #for days
    standard_number_of_digits_re_1 = r"(?:del dia|de el dia|el dia|del|de el|el)[\s|]*(\b\d)"
    standard_number_of_digits_re_2 = r"(\b\d)[\s|]*º[\s|]*dia"
    
    #for months
    standard_number_of_digits_re_3 = r"(?:del mes|de el mes|del|de el)[\s|]*(\b\d)"
    standard_number_of_digits_re_4 = r"(?:del mes|de el mes|del|de el)[\s|]*(\b\d)[\s|]*(?:º[\s|]*mes del año|º[\s|]*mes)"
    
    
    #replacement with this conditions, and put '0' in front a day number only if it is one number and not two(or more numbers)
    #  example: '1' --> '01'  or  '10' --> '10'
    input_text = re.sub(standard_number_of_digits_re_3, r"0\1", input_text)
    
    print(repr(input_text)) #output
    
    input_text = re.sub(standard_number_of_digits_re_4, r"0\1", input_text)
    
    print(repr(input_text)) #output
    
    input_text = re.sub(standard_number_of_digits_re_1, r"0\1", input_text)
    
    print(repr(input_text)) #output
    
    input_text = re.sub(standard_number_of_digits_re_2, r"0\1", input_text)
    
    print(repr(input_text)) #output
    

    The problem is for example in the example 3 :

    'Hay 10 unidades para 015 012 y seran 9 ya para 07 de noviembre'
    

    And the correct output is:

    'Hay 10 unidades para 15 12 y seran 9 ya para 07 de noviembre'
    

    CodePudding user response:

    Get rid of \b after \d{1}. Python considers º to be a word character, so there's no word boundary between 7 and º. You don't need to match a word boundary, since the regexp only allows spaces or | between the number and º.

    There's also no need for {1}. All patterns match 1 time unless they're quantified, so {1} is redundant.

    (\b\d)[\s|]*º[\s|]*dia
    

    https://regex101.com/r/84QDbp/1

  • Related