Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!cs.uu.nl!news.stack.nl!newsfeed.xs4all.nl!newsfeed2.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.001 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'prefix': 0.07; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'string)': 0.09; 'terry': 0.09; 'def': 0.10; 'applies': 0.15; 'itertools': 0.16; 'lambda': 0.16; 'nick': 0.16; 'omitted.': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'reedy': 0.16; 'string': 0.17; 'wrote:': 0.17; 'jan': 0.18; '>>>': 0.18; 'skip:p 30': 0.20; 'import': 0.21; '(all': 0.22; 'subject:skip:i 10': 0.22; 'split': 0.23; 'this:': 0.23; 'idea': 0.24; 'header:In-Reply-To:1': 0.25; 'header:User-Agent:1': 0.26; 'am,': 0.27; 'header:X-Complaints-To:1': 0.28; 'lines': 0.28; 'description,': 0.29; 'remains': 0.29; 'case,': 0.29; 'words': 0.29; "skip:' 10": 0.30; 'file': 0.32; "skip:' 20": 0.32; 'to:addr :python-list': 0.33; 'text': 0.34; 'list': 0.35; 'fresh': 0.35; 'list.': 0.35; 'received:org': 0.36; 'two': 0.37; 'subject:: ': 0.38; 'skip:l 20': 0.38; 'things': 0.38; 'description': 0.39; 'to:addr:python.org': 0.39; 'skip:" 10': 0.40; 'header:Received:5': 0.40; 'end': 0.40; 'red': 0.60; 'said:': 0.65; 'received:fios.verizon.net': 0.84; 'words)': 0.84; 'subject:Good': 0.91 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Terry Reedy Subject: Re: Good use for itertools.dropwhile and itertools.takewhile Date: Tue, 04 Dec 2012 15:44:10 -0500 References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: pool-173-75-251-66.phlapa.fios.verizon.net User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20121026 Thunderbird/16.0.2 In-Reply-To: X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 54 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1354653865 news.xs4all.nl 6856 [2001:888:2000:d::a6]:46644 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:34252 On 12/4/2012 8:57 AM, Nick Mellor wrote: > I have a file full of things like this: > > "CAPSICUM RED fresh from Queensland" > > Product names (all caps, at start of string) and descriptions (mixed > case, to end of string) all muddled up in the same field. And I need > to split them into two fields. Note that if the text had said: > > "CAPSICUM RED fresh from QLD" > > I would want QLD in the description, not shunted forwards and put in > the product name. So (uncontrived) list comprehensions and regex's > are out. > > I want to split the above into: > > ("CAPSICUM RED", "fresh from QLD") > > Enter dropwhile and takewhile. 6 lines later: > > from itertools import takewhile, dropwhile > def split_product_itertools(s): > words = s.split() > allcaps = lambda word: word == word.upper() > product, description =\ > takewhile(allcaps, words), dropwhile(allcaps, words) > return " ".join(product), " ".join(description) If the original string has no excess whitespace, description is what remains of s after product prefix is omitted. (Py 3 code) from itertools import takewhile def allcaps(word): return word == word.upper() def split_product_itertools(s): product = ' '.join(takewhile(allcaps, s.split())) return product, s[len(product)+1:] print(split_product_itertools("CAPSICUM RED fresh from QLD")) >>> ('CAPSICUM RED', 'fresh from QLD') Without that assumption, the same idea applies to the split list. def split_product_itertools(s): words = s.split() product = list(takewhile(allcaps, words)) return ' '.join(product), ' '.join(words[len(product):]) -- Terry Jan Reedy