Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.freenet.ag!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!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 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'example:': 0.03; '-----------': 0.04; 'elif': 0.04; 'python)': 0.05; '------------': 0.07; 'data:': 0.07; 'executable': 0.07; 'subject:file': 0.07; 'excluding': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subject:create': 0.09; 'files.': 0.13; 'resulting': 0.13; '(the': 0.15; '#no': 0.16; 'csv': 0.16; 'duplicates': 0.16; 'feasible': 0.16; 'in-memory': 0.16; 'increment': 0.16; 'one)': 0.16; 'operation.': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'row': 0.16; 'appears': 0.18; 'feb': 0.19; 'module': 0.19; 'skip:= 10': 0.20; 'file.': 0.20; 'sort': 0.21; 'file:': 0.22; 'keys': 0.22; 'second': 0.24; 'values': 0.26; 'plain': 0.27; 'header:X -Complaints-To:1': 0.28; 'lines': 0.28; 'rest': 0.28; '(unless': 0.29; 'invoke': 0.29; 'probably': 0.29; 'skip:- 30': 0.31; 'file': 0.32; 'url:home': 0.33; 'anyone': 0.33; 'to:addr:python-list': 0.33; 'hi,': 0.33; 'skip:d 20': 0.34; 'text': 0.34; 'third': 0.34; 'thanks': 0.34; 'skip:k 20': 0.35; 'received:org': 0.36; 'charset :us-ascii': 0.36; 'being': 0.37; 'data': 0.37; 'subject:: ': 0.38; 'to:addr:python.org': 0.39; 'where': 0.40; 'header:Received:5': 0.40; 'help': 0.40; 'your': 0.60; 'first': 0.61; 'more': 0.63; '2013': 0.84; 'dennis': 0.91 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Dennis Lee Bieber Subject: Re: Read csv file and create a new file Date: Thu, 28 Feb 2013 21:04:32 -0500 Organization: > Bestiaria Support Staff < References: <512fac9c$0$40355$4fafbaef@reader1.news.tin.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: adsl-76-253-101-185.dsl.klmzmi.sbcglobal.net X-Newsreader: Forte Agent 3.3/32.846 X-No-Archive: YES 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: 72 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1362103483 news.xs4all.nl 6873 [2001:888:2000:d::a6]:58774 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:40211 On 28 Feb 2013 19:14:36 GMT, io declaimed the following in gmane.comp.python.general: > Hi, > > i have to files. > > First file is a csv file > Second file is a plain text file where each row has a value (text) > > I want to be able to create a third file using data from the first file > excluding the values listed in the second file. > > Example: > > First file: > ----------- > > mtgoxeur 12 24 36 > mtgoxusd 10 12 14 > mtgoxpln 2 4 6 > > > Second file: > ------------ > > mtgoxusd > > > > Third File (the resulting one) : > -------------------------------- > > mtgoxeur 12 24 36 > mtgoxpln 2 4 6 > > > > Thanks to anyone that can help > This appears to be a variation of standard sort/merge operation. The variation being that you /do not/ write lines of one file when they match the other file. While an in-memory sort may be feasible (unless the data file is extremely large) I would probably invoke your OS sort module on each file... Then (pseudo-code, not executable python) data = csvin.next() key = keyfile.readln().strip() while data and key: if data[0] < key: csvout.write(data) data = datafile.readln().strip() elif data[0] = key: data =csvin.next() #don't increment key to catch duplicates in data elif data[0] > key: key = keyfile.readln().strip() while data: #no more keys to remove, copy rest of data file csvout.write(data) data = csvin.next() -- Wulfraed Dennis Lee Bieber AF6VN wlfraed@ix.netcom.com HTTP://wlfraed.home.netcom.com/