Path: csiph.com!usenet.pasdenom.info!news.albasani.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 0.026 X-Spam-Evidence: '*H*': 0.95; '*S*': 0.00; 'ascii': 0.07; 'bytes)': 0.09; 'linux.': 0.09; 'stored': 0.10; ':-)': 0.13; 'inputs': 0.16; 'oct': 0.16; 'processed.': 0.16; 'sequential': 0.16; 'written.': 0.16; 'wrote:': 0.17; 'variables': 0.17; 'input': 0.18; 'windows': 0.19; 'to:name:python-list@python.org': 0.20; 'written': 0.20; 'meant': 0.21; 'finally,': 0.22; "i'd": 0.22; 'installed': 0.23; 'external': 0.24; 'linux': 0.24; 'tried': 0.25; 'header:In-Reply- To:1': 0.25; 'header:User-Agent:1': 0.26; '---': 0.26; 'charset:iso-8859-15': 0.26; '(e.g.': 0.27; 'question': 0.27; 'giant': 0.29; 'thus,': 0.29; 'probably': 0.29; 'install': 0.29; 'performing': 0.30; 'file': 0.32; 'ram': 0.33; 'problem': 0.33; 'to:addr:python-list': 0.33; 'thanks': 0.34; 'saved': 0.35; 'pm,': 0.35; 'data.': 0.36; 'subject: (': 0.36; 'being': 0.37; 'rather': 0.37; 'data': 0.37; 'subject:: ': 0.38; 'perform': 0.38; 'files': 0.38; 'some': 0.38; 'several': 0.39; 'to:addr:python.org': 0.39; 'received:192': 0.39; 'received:192.168': 0.40; 'subject:-': 0.40; 'save': 0.61; 'first': 0.61; 'series': 0.63; 'skip:n 10': 0.63; 'reverse': 0.65; 'forward': 0.66; 'manner': 0.74; 'received:213.150': 0.84; 'subject:Fast': 0.84; 'subject:read': 0.84; 'subject:write': 0.84; 'rusi': 0.91 X-SENDER-IP: [213.112.50.224] X-LISTENER: [smtp.bredband.net] X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AkolAJT+iFDVcDLgOWdsb2JhbAANN4pQt2oBAQEBIReCUgEBAQEDOEARCxgJFg8JAwIBAgExFAYNCAEBsWuTV4thhm0DkkKWYA X-IronPort-AV: E=Sophos;i="4.80,646,1344204000"; d="scan'208";a="139342571" Date: Thu, 25 Oct 2012 11:00:59 +0200 From: Virgil Stokes User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: "python-list@python.org" Subject: Re: Fast forward-backward (write-read) References: <069780e5-43ee-48de-9257-fc0f16ec39d7@s9g2000pbh.googlegroups.com> In-Reply-To: <069780e5-43ee-48de-9257-fc0f16ec39d7@s9g2000pbh.googlegroups.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit 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: 20 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1351155659 news.xs4all.nl 6911 [2001:888:2000:d::a6]:56124 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:32097 On 24-Oct-2012 17:11, rusi wrote: > On Oct 23, 7:52 pm, Virgil Stokes wrote: >> I am working with some rather large data files (>100GB) that contain time series >> data. The data (t_k,y(t_k)), k = 0,1,...,N are stored in ASCII format. I perform >> various types of processing on these data (e.g. moving median, moving average, >> and Kalman-filter, Kalman-smoother) in a sequential manner and only a small >> number of these data need be stored in RAM when being processed. When performing >> Kalman-filtering (forward in time pass, k = 0,1,...,N) I need to save to an >> external file several variables (e.g. 11*32 bytes) for each (t_k, y(t_k)). These >> are inputs to the Kalman-smoother (backward in time pass, k = N,N-1,...,0). >> Thus, I will need to input these variables saved to an external file from the >> forward pass, in reverse order --- from last written to first written. >> >> Finally, to my question --- What is a fast way to write these variables to an >> external file and then read them in backwards? > Have you tried gdbm/bsddbm? They are meant for such (I believe). > Probably needs to be installed for windows; works for linux. > If I were you I'd try out with the giant data on linux and see if the > problem is solved, then see how to install for windows Thanks Rusi :-)