Extracting patterns after matching a regex

nn pruebauno at latinmail.com
Tue Sep 8 16:21:39 CEST 2009


On Sep 8, 9:55 am, "Mart." <mdeka... at gmail.com> wrote:
> On Sep 8, 2:16 pm, "Andreas Tawn" <andreas.t... at ubisoft.com> wrote:
>
>
>
> > > Hi,
>
> > > I need to extract a string after a matching a regular expression. For
> > > example I have the string...
>
> > > s = "FTPHOST: e4ftl01u.ecs.nasa.gov"
>
> > > and once I match "FTPHOST" I would like to extract
> > > "e4ftl01u.ecs.nasa.gov". I am not sure as to the best approach to the
> > > problem, I had been trying to match the string using something like
> > > this:
>
> > > m = re.findall(r"FTPHOST", s)
>
> > > But I couldn't then work out how to return the "e4ftl01u.ecs.nasa.gov"
> > > part. Perhaps I need to find the string and then split it? I had some
> > > help with a similar problem, but now I don't seem to be able to
> > > transfer that to this problem!
>
> > > Thanks in advance for the help,
>
> > > Martin
>
> > No need for regex.
>
> > s = "FTPHOST: e4ftl01u.ecs.nasa.gov"
> > If "FTPHOST" in s:
> >     return s[9:]
>
> > Cheers,
>
> > Drea
>
> Sorry perhaps I didn't make it clear enough, so apologies. I only
> presented the example  s = "FTPHOST: e4ftl01u.ecs.nasa.gov" as I
> thought this easily encompassed the problem. The solution presented
> works fine for this i.e. re.search(r'FTPHOST: (.*)',s).group(1). But
> when I used this on the actual file I am trying to parse I realised it
> is slightly more complicated as this also pulls out other information,
> for example it prints
>
> e4ftl01u.ecs.nasa.gov\r\n', 'FTPDIR: /PullDir/0301872638CySfQB\r\n',
> 'Ftp Pull Download Links: \r\n', 'ftp://e4ftl01u.ecs.nasa.gov/PullDir/
> 0301872638CySfQB\r\n', 'Down load ZIP file of packaged order:\r\n',
>
> etc. So I need to find a way to stop it before the \r
>
> slicing the string wouldn't work in this scenario as I can envisage a
> situation where the string lenght increases and I would prefer not to
> keep having to change the string.
>
> Many thanks

It is not clear from your post what the input is really like. But just
guessing this might work:

>>> print s
'MEDIATYPE: FtpPull\r\n', 'MEDIAFORMAT: FILEFORMAT\r\n','FTPHOST:
e4ftl01u.ecs.nasa.gov\r\n', 'FTPDIR: /PullDir/0301872638CySfQB\r
\n','Ftp Pull Download Links: \r\n'

>>> re.search(r'FTPHOST: (.*?)\\r',s).group(1)
'e4ftl01u.ecs.nasa.gov'



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