String formatting (%)

[Peter Hansen]

Daniel 'Dang' Griffith wrote:

> On Wed, 28 Apr 2004 09:15:02 -0400, Peter Hansen <peter at engcorp.com>
> wrote:
>>I suspect there's also a regular expression that could deal with
>>that, but I don't want to know what it is. ;-)
> 
>     Since you don't want to know what it is, I'll at least tell you
> where it is: In Mastering Regular Expressions by Jeffrey E. F. Friedl.
> I don't have it front of me, but it's the "commafying" example.  A
> quick search of the author's site looks like it's on pgs 64-65.  

Thank you.  You can even get the code listings online, which is
very nice since my copy has migrated into a closet during a recent
move.

 >>> import re
 >>> s = '21421906.12'
 >>>
 >>> re.sub(r'(?<=\d)(?=(\d\d\d)+\.)', ',', s)
'21,421,906.12'

>     Of course, the OP would substitute spaces for the commas.

 >>> _.replace(',', ' ')
'21 421 906.12'

Very nice... quite elegant, I suppose.  I struggled with it a
bit myself yesterday but I'm no RE expert. :-(

-Peter