Re: What is the most efficient way to compare similar contents in two lists?

Path	csiph.com!x330-a1.tempe.blueboxinc.net!feeder1.hal-mli.net!news.glorb.com!postnews.google.com!gh5g2000vbb.googlegroups.com!not-for-mail
From	Zachary Dziura <zcdziura@gmail.com>
Newsgroups	comp.lang.python
Subject	Re: What is the most efficient way to compare similar contents in two lists?
Date	Mon, 13 Jun 2011 08:21:29 -0700 (PDT)
Organization	http://groups.google.com
Lines	21
Message-ID	<bad3a56e-efba-4ef4-a159-64273cda5a08@gh5g2000vbb.googlegroups.com> (permalink)
References	<3ff2f4cc-7c26-4f59-9463-d6f0874174d8@dn9g2000vbb.googlegroups.com> <mailman.169.1307977750.11593.python-list@python.org>
NNTP-Posting-Host	192.223.243.5
Mime-Version	1.0
Content-Type	text/plain; charset=ISO-8859-1
Content-Transfer-Encoding	quoted-printable
X-Trace	posting.google.com 1307978489 12053 127.0.0.1 (13 Jun 2011 15:21:29 GMT)
X-Complaints-To	groups-abuse@google.com
NNTP-Posting-Date	Mon, 13 Jun 2011 15:21:29 +0000 (UTC)
Complaints-To	groups-abuse@google.com
Injection-Info	gh5g2000vbb.googlegroups.com; posting-host=192.223.243.5; posting-account=W6anpAoAAABCcU4OKFSlcJpyVgvwTcuB
User-Agent	G2/1.0
X-Google-Web-Client	true
X-Google-Header-Order	HUALSRCENK
X-HTTP-UserAgent	Mozilla/5.0 (Windows NT 5.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1,gzip(gfe)
Xref	x330-a1.tempe.blueboxinc.net comp.lang.python:7520

Show key headers only | View raw

On Jun 13, 11:09 am, Chris Angelico <ros...@gmail.com> wrote:
> On Tue, Jun 14, 2011 at 12:58 AM, Zachary Dziura <zcdzi...@gmail.com> wrote:
> > if set(source_headers) == set(target_headers):
> >    similar_headers = len(source_headers)
>
> Since you're making sets already, I'd recommend using set operations -
> same_headers is the (length of the) intersection of those two sets,
> and different_headers is the XOR.
>
> # If you need the lists afterwards, use different variable names
> source_headers = set(source_headers)
> target_headers = set(target_headers)
> similar_headers = len(source_headers & target_headers)
> different_headers = len(source_headers ^ target_headers)
>
> Chris Angelico

Wow! That was a lot easier than I thought it would be! I guess I
should have done a little bit more research into such operations.
Thanks a bunch!!

Thread

csiph-web