Python re to extract useful information from each line
Tim Chase
python.list at tim.thechases.com
Wed Apr 29 18:38:57 EDT 2015
On 2015-04-29 14:22, Emile van Sebille wrote:
> On 4/29/2015 1:49 PM, Kashif Rana wrote:
> > pol_elements =
> > re.compile('id\s(?P<p_id>.+?)(?:\sname\s(?P<p_name>.+?))?\sfrom\s(?P<p_from>.+?)\sto\s(?P<p_to>.+?)\s{2}(?P<p_src>[^\s]+?)\s(?P<p_dst>[^\s]+?)\s(?P<p_port>[^\s]+?)(?:(?P<p_nat_status>\snat)\s(?P<p_nat_type>[^\s]+?)(?P<p_nat_ip>\sdip-id\s[^\s]+?)?)?\s(?P<p_action>[^\s]+?)(?:\sschedule\s(?P<p_schedule>[^\s]+?))?(?P<p_log_status>\slog)?$'
> > )
>
> ... and that's why we avoid regular expressions... it makes my head
> hurt just looking at that line noise.
First, it appears the OP isn't using raw strings which make those
back-slashes just ask for trouble.
That said, it would be a lot better if the OP made use of re.VERBOSE
to put each component on its own line:
pol_elements = re.compile(r"""
id
\s
(?P<p_id>.+?)
(?:
\s
name
\s
(?P<p_name>.+?)
)?
\s
from
\s
(?P<p_from>.+?)
\s
to
\s
(?P<p_to>.+?)
\s{2}
(?P<p_src>[^\s]+?)
\s
(?P<p_dst>[^\s]+?)
\s(?P<p_port>[^\s]+?)
(?:
\s
(?P<p_nat_status>nat)
\s
(?P<p_nat_type>\w+)
(
\s?
P<p_nat_src_ip>dip-id
\s
\d+
)?
(
\s
ip
\s
(?P<p_nat_dst_ip>[\d\.]+)
\s
port
(?P<dst_nat_port>\d+)
)?
)?
\s
(?P<p_action>[^\s]+?)
(?:
\s
schedule
\s
(?P<p_schedule>[^\s]+?)
)?
(?P<p_log_status>\slog)?
$
""", re.VERBOSE)
which, with some copious comments in the expression, would make it
almost readable.
Alternatively, switch to an actual parser like pyparsing.
-tkc
More information about the Python-list
mailing list