In article <mailman.5437.1389689219.18130.python-l...@python.org>,
Igor Korot <ikoro...@gmail.com> wrote:
> Hi, ALL,
> I'm trying to process a file which has following lines:
>
> 192.168.1.6 > 192.168.1.7: ICMP echo request, id 100, seq 200, length 30
>
> (this is the text file out of tcpdump)
>
> Now I can esily split the line twice: once by ':' symbol to separate
> address and the protocol information and the second time by ',' to get
> information about the protocol.
> However, I don't need all the protocol info. All I'm interested in is
> the last field, which is length.
One possibility would be to forget about all the punctuation and just
use "length " (note the trailing space) as the split delimiter:
>>> line = '192.168.1.6 > 192.168.1.7: ICMP echo request, id 100, seq
200, length 30'
>>> line.split('length ')
'30'
this will only work if you're sure that "length " can never appear
anywhere else in the line. Another, perhaps more idiomatic, way would
be:
>>> _, length = line.split('length ')
>>> print length
30
What's happening here is split() is returning a list of two items, which
you then unpack into two variables, "_" and "length". It's common to
unpack unwanted fields into "_", as a hint (to the reader) that it's
unused.
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