Ask for help on using re

[ast]

Le 05/08/2021 à 17:11, ast a écrit :
> Le 05/08/2021 à 11:40, Jach Feng a écrit :
>> I want to distinguish between numbers with/without a dot attached:
>>
>>>>> text = 'ch 1. is\nch 23. is\nch 4 is\nch 56 is\n'
>>>>> re.compile(r'ch \d{1,}[.]').findall(text)
>> ['ch 1.', 'ch 23.']
>>>>> re.compile(r'ch \d{1,}[^.]').findall(text)
>> ['ch 23', 'ch 4 ', 'ch 56 ']
>>
>> I can guess why the 'ch 23' appears in the second list. But how to get 
>> rid of it?
>>
>> --Jach
>>
> 
>  >>> import re
> 
>  >>> text = 'ch 1. is\nch 23. is\nch 4 is\nch 56 is\n'
> 
>  >>> re.findall(r'ch \d+\.', text)
> ['ch 1.', 'ch 23.']
> 
>  >>> re.findall(r'ch \d+(?!\.)', text)   # (?!\.) for negated look ahead
> ['ch 2', 'ch 4', 'ch 56']

import regex

# regex is more powerful that re

 >>> text = 'ch 1. is\nch 23. is\nch 4 is\nch 56 is\n'

 >>> regex.findall(r'ch \d++(?!\.)', text)

['ch 4', 'ch 56']

## ++ means "possessive", no backtrack is allowed