[Tutor] backreferences - \0

[Lie Ryan]

On 06/06/10 19:36, Payal wrote:
> On Sun, Jun 06, 2010 at 06:26:18PM +1000, Steven D'Aprano wrote:
>> Two things. Firstly, the Python regex engine numbers backreferences from 
>> 1, not 0, so you need \1 and not \0.
> 
> Thank for the mail, but i am still not getting it. e.g.
<snip>
> 
> In first sub I expected,
> one two - one two
> 
> I understand that \1 is first (group), \2 the second and etc.
> But what is the entire regex?


>>> re.sub('(one) (two)', r'\g<0> - \1 \2',s)

the \g<number> is equivalent to \number but is intended to ambiguate
cases like "\g<2>0" vs. "\20". It happens that \g<0> refers to the
entire group.