Finding all regex matches by index?

[Roy Smith]

In article <roy-ACBB94.21332929052012 at news.panix.com>,
 Roy Smith <roy at panix.com> wrote:

> I have a long string (possibly 100s of Mbytes) that I want to search for 
> regex matches.  re.finditer() is *almost* what I want, but the problem 
> is that it returns matching strings.  What I need is a list of offsets 
> in the string where the regex matched.  Thus:
> 
> s = "this is a string"
> find("is", s) => [2, 5]
> 
> Is there anything that does this?

Ugh, looks like I simply mis-read the docs.  findall() returns strings, 
finditer() returns match objets (which is what I need).  Duh.