Path: csiph.com!aioe.org!news.stack.nl!newsfeed.xs4all.nl!newsfeed5.news.xs4all.nl!xs4all!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 0.022 X-Spam-Evidence: '*H*': 0.96; '*S*': 0.00; '"c"': 0.07; 'dict': 0.09; 'dynamically': 0.09; 'def': 0.13; 'simplified': 0.16; 'val': 0.16; 'worried': 0.16; '\xc2\xa0i': 0.16; "\xc2\xa0i'm": 0.16; 'cc:addr :python-list': 0.16; 'wed,': 0.17; 'subject:Help': 0.17; 'wrote:': 0.18; 'converted': 0.18; 'cheers,': 0.20; 'cc:no real name:2**0': 0.21; "doesn't": 0.22; 'header:In-Reply-To:1': 0.22; 'feb': 0.22; 'received:209.85.212.46': 0.23; 'received:mail- vw0-f46.google.com': 0.23; 'helper': 0.23; 'levels.': 0.23; 'pieces': 0.23; 'generic': 0.24; 'subject:data': 0.25; 'cc:2**0': 0.26; 'code': 0.26; 'figure': 0.26; 'bit': 0.28; "i'm": 0.28; 'message-id:@mail.gmail.com': 0.29; 'mapping': 0.29; 'example': 0.29; 'problem': 0.29; 'print': 0.29; 'cc:addr:python.org': 0.29; 'pm,': 0.29; 'objects.': 0.30; 'chris': 0.30; "i've": 0.32; 'received:209.85.212': 0.33; "can't": 0.33; 'it.': 0.33; 'hi,': 0.34; 'nested': 0.34; 'problem.': 0.35; 'something': 0.35; 'lists,': 0.35; 'like,': 0.37; 'pull': 0.37; 'but': 0.37; 'received:google.com': 0.37; 'received:209.85': 0.38; 'some': 0.38; 'data': 0.38; 'open': 0.38; 'e.g.': 0.39; "i'd": 0.39; 'subject:from': 0.39; 'received:209': 0.39; 'might': 0.40; 'header:Received:6': 0.61; 'your': 0.61; '29,': 0.73; 'introduce': 0.82; "'2',": 0.84; 'querying': 0.84; 'sender:addr:chris': 0.84; 'subject:different': 0.84; 'thin': 0.84; 'to:addr:hotmail.com': 0.89; 'fortunately': 0.91 Received-SPF: pass (google.com: domain of chris@rebertia.com designates 10.52.90.20 as permitted sender) client-ip=10.52.90.20; Authentication-Results: mr.google.com; spf=pass (google.com: domain of chris@rebertia.com designates 10.52.90.20 as permitted sender) smtp.mail=chris@rebertia.com; dkim=pass header.i=chris@rebertia.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rebertia.com; s=google; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=a878ceygNLUxS+HnmGXwLO0Z5e5b6P85dJCXFIrkwts=; b=CU2COjvchF5S40OXEzi6QrHQx3xqL5qtCxAZ7/Q5bE9YU1H69P85gDRgSCEPm94gwy LDyVXYxZ0uf0hDunhkcKT06hcYXa6ASBisRvVv3f4+7ER9btrHlsVUR++LUjFqduxpSH SC6be31gAATPM/TZsxjGD1+lz6tO2BhP/tcy4= MIME-Version: 1.0 Sender: chris@rebertia.com In-Reply-To: References: Date: Wed, 29 Feb 2012 20:43:44 -0800 X-Google-Sender-Auth: 5XarX7mICwYuzjiAFsRmymlVrfk Subject: Re: Help needed: dynamically pull data from different levels of a dict From: Chris Rebert To: Peter Rubenstein Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Gm-Message-State: ALoCoQmt5kFG0Bs3CtvtPHxAT1u/8mwsCmSFSVp3PqOJS5QoRoEaY/Qrt44JjsauFD4eXSv8lQpG Cc: python-list@python.org 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: 57 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1330577028 news.xs4all.nl 6917 [2001:888:2000:d::a6]:38672 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:21065 On Wed, Feb 29, 2012 at 7:56 PM, Peter Rubenstein wrote: > Hi, > > I'd appreciate a bit of help on this problem. =C2=A0I have some data that= I've > converted to a dict and I want to pull out individual pieces of it. > > Simplified version-- > > a=3D{'1':'a', '2':'b', '3':{4:'d'}, '5':{'6': {'7': [ {'8':'e'}, {'9':'f'= } ] } > } } > > I'd like to be able to code something like: > > data_needed =3D ['1', '2', '3:4', '5:6:7-8'] > for val in data_needed: > =C2=A0 =C2=A0 answer=3Dextract_from(a,val) > =C2=A0 =C2=A0 print answer > > And get: > a > b > c "c" apparently sprung completely out of thin air... > d > e > > Problem is I can't figure out what extract_from would look like, such tha= t > it would proceed dynamically down to the right level. =C2=A0I'm open to t= he > possibility that I'm not approaching this the right way. data_needed =3D ['1', '2', ('3', '4'), ('5', '6', '7', 0, '8')] def extract_from(mapping, key_path): current =3D mapping for key in key_path: current =3D current[key] return current I would perhaps try and restructure the data into something less generic than nested dicts & lists, e.g. objects. You then might be able to introduce helper querying methods. I would also be worried about Law of Demeter violations, but fortunately your concrete example doesn't reach any deeper than 2 levels. Cheers, Chris -- http://chrisrebert.com