Path: csiph.com!eeepc.pasdenom.info!news.pasdenom.info!news.dougwise.org!gegeweb.org!de-l.enfer-du-nord.net!feeder1.enfer-du-nord.net!weretis.net!feeder4.news.weretis.net!news.mixmin.net!news2.arglkargh.de!news.wiretrip.org!newsfeed.xs4all.nl!newsfeed5.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 0.012 X-Spam-Evidence: '*H*': 0.98; '*S*': 0.00; 'python.': 0.05; 'variant': 0.07; 'python': 0.08; 'collections': 0.09; 'counting': 0.09; 'skip:[ 30': 0.09; '>>>': 0.11; 'places.': 0.16; 'writes:': 0.17; 'values': 0.18; 'header:In-Reply-To:1': 0.23; 'appropriate': 0.25; 'code': 0.25; 'handling': 0.25; '(in': 0.25; 'paul': 0.27; 'curious': 0.28; 'message-id:@mail.gmail.com': 0.29; 'decimal': 0.30; 'digits': 0.30; 'import': 0.31; 'to:addr:python-list': 0.31; 'actually': 0.31; 'ways': 0.34; 'print': 0.35; 'another': 0.35; 'using': 0.35; 'but': 0.36; 'table': 0.36; 'tool': 0.36; 'received:209.85': 0.38; 'received:google.com': 0.38; 'might': 0.38; 'skip:t 20': 0.38; 'actual': 0.39; 'subject:: ': 0.39; 'to:addr:python.org': 0.40; 'records': 0.65; 'atleast': 0.84; 'records:': 0.84; 'frequency': 0.93 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=O33NDXZV69wp2yJdI0UfERRkt7LpAi1T4R/6+ExBQxs=; b=EOmvymVcd4DNH1n6NxOEs+iK5cpXmuKFcMaIuUkXCFkos/KUAER/s++ROj9gcjfDAI 2lxyRDd7jUx7OM1qOyatRuffEXYcuBCuwc9qgSVDm+C6Ja3X9ITMkQbqVCZBLul2ET0o XCYl5EBU1ySmwr1zYhoDqIF6yuUjZO2UIozUc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=RcDxM6/2qY2X8F5GOI8xS/q2VpOClRxYPfFSgQWUUcCSabuij9d6zK1tMgzUMcGjb+ GGyO7akWiQjMo5hRvDJ8lpgiZ9xwYuKPyElSjAeff3Afkj4WHmZ8KHB6XwzB3izDv4Jx 06NeUjnwCtM6OBVoXyeBb3ZzPF1WguMzFfcOI= MIME-Version: 1.0 In-Reply-To: <7x7hdarzol.fsf@ruckus.brouhaha.com> References: <2f463773-da89-4c50-bd4f-8f891e6038a7@d12g2000vbz.googlegroups.com> <7x7hdarzol.fsf@ruckus.brouhaha.com> Date: Tue, 8 Feb 2011 23:25:43 +0100 Subject: Re: frequency of values in a field From: Vlastimil Brom To: python-list@python.org Content-Type: text/plain; charset=ISO-8859-1 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 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: 37 NNTP-Posting-Host: 82.94.164.166 X-Trace: 1297203945 news.xs4all.nl 81482 [::ffff:82.94.164.166]:38230 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:55727 2011/2/8, Paul Rubin : > noydb writes: >> I am looking for ways to go about capturing the frequency of unique >> values in one field in a dbf table which contains ~50k records. The >> values are numbers with atleast 5 digits to the right of the decimal, >> but I want the frequency of values to only 2 decimal places. I do >> have a method to do this courtesy of a provided tool in ArcGIS. Was >> just curious about ways to do it without arcgis sw, using just python. >... > > from decimal import Decimal as D > from collections import defaultdict > > records = ['3.14159','2.71828','3.142857'] > > td = defaultdict(int) > for x in records: > td[D(x).quantize(D('0.01'))] += 1 > > print td > >>... Another variant of the above code using collections.Counter (in newer python versions); The actual frequency counting code is actually the single instantiation of the Counter from an iterable. The appropriate handling of the number values might be tweaked as needed. >>> from decimal import Decimal as D >>> from collections import Counter >>> records = ['3.14159','2.71828','3.142857'] >>> Counter(D(x).quantize(D('0.01')) for x in records) Counter({Decimal('3.14'): 2, Decimal('2.72'): 1}) >>> vbr