Ask for help on using re

[Jach Feng]

Neil 在 2021年8月5日 星期四下午6:36:58 [UTC+8] 的信中寫道：
> Jach Feng <jf... at ms4.hinet.net> wrote: 
> > 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
> Does 
> 
> >>> re.findall(r'ch\s+\d+(?![.\d])',text) 
> 
> do what you want? This matches "ch", then any nonzero number of 
> whitespaces, then any nonzero number of digits, provided this is not 
> followed by a dot or another digit.

Yes, the result is what I want. Thank you, Neil!

The solution is more complex than I expect. Have to digest it:-)

--Jach