Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail From: Ian Kelly Newsgroups: comp.lang.python Subject: Re: Slice equivalent to dict.get Date: Thu, 31 Mar 2016 09:43:50 -0600 Lines: 14 Message-ID: References: <56fd3d17$0$1606$c3e8da3$5496439d@news.astraweb.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: news.uni-berlin.de ZE+LBZfGEbbRHNHSxoJh1wHob6M3zSYOYKBv9S8UHL8A== Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.027 X-Spam-Evidence: '*H*': 0.95; '*S*': 0.00; 'indexing': 0.07; "'default'": 0.09; '-1,': 0.09; 'indexes': 0.09; 'def': 0.13; 'explicitly': 0.15; 'thu,': 0.15; '2016': 0.16; 'received:io': 0.16; 'received:psf.io': 0.16; 'wrote:': 0.16; 'first,': 0.20; '31,': 0.22; 'am,': 0.23; 'header:In-Reply-To:1': 0.24; 'message- id:@mail.gmail.com': 0.27; 'idea': 0.28; 'index,': 0.29; 'skip:[ 10': 0.31; "can't": 0.32; 'received:google.com': 0.35; 'trouble': 0.35; 'but': 0.36; 'received:209.85': 0.36; 'to:addr:python-list': 0.36; 'subject:: ': 0.37; 'received:209.85.213': 0.37; 'seem': 0.37; 'things': 0.38; 'received:209': 0.38; 'end': 0.39; 'to:addr:python.org': 0.40; 'more': 0.63; 'between': 0.65; 'mar': 0.65; 'note:': 0.66; 'otten': 0.84; 'pain': 0.84; 'to:name:python': 0.84 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=vv2uWuc6AXSyyICbs7OzMZvFFXMLpOZTO8OF+I43wMw=; b=H0ANqAo8NQIe698/AfIbo8QnHmxsoMOC1vc/bLfYbT/qCAZ2pjzG6pucZaVVcvYQUN WFa+FAh9Zm4slPX6bM0edFcHs4r2Ef5nc0l+xtwvUUIrtKoKglHZghfrN72wg1IzTena w5h6qVhCfCDTchDMKrblBIQwyqk7eBkdFdz0CEBZcl0gzgfWO7lrEPQ/5M4Y/DuHwvX5 spX8LOF8OIenWMyLMVOG0NfRfWIbtPdwML7oqAaGYfPXYGYwVrJqYDZpAa7sxqIA4dFe TbuVoA2JRkEoK2FE20aGSRwTOFnXWlTQ7UzOoBSPP34yFLAqyZoXtsTNzL+/3aliqWGE i51g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=vv2uWuc6AXSyyICbs7OzMZvFFXMLpOZTO8OF+I43wMw=; b=EViC7AIhhwKVayQ99IS1iDCT3ICXZMCuh2FAEG2zvUweEsjGYUHZ3cKwHkSrp9swVN wYAlJHHOmehlynisLmiDlPFvd1q2eu9gQ8qtUjHmxlIzXEcny6pFqazXmk/DlMbtHtOa N4AIAWBZs+DkGSHzxewHtxRZyfIJvNz0e422vvA+LusO2Oossfr6QNoK9CvskE7WiBHl +X/i0Or9Fl0r49uhOz4+8Pshsr/HZ7jT4B2HY/W/a+A7+hGESzWWJO9sDSO4lpbDw9QR t3oGRVeVoriCvqSZPVJ5upm95BiEk5zPlVe98pgoiBQtxHvPK4Sv1ekcHZ17TRlN1sWu Kixw== X-Gm-Message-State: AD7BkJLDsxHMrhKhDjdGoreKJTCnrU/f5+f7vH9UGRIJqxm0Sf5aVUwsfPxu4cTgN8v8z93eJz2kR51+0yBNPA== X-Received: by 10.50.131.201 with SMTP id oo9mr3576720igb.68.1459439070035; Thu, 31 Mar 2016 08:44:30 -0700 (PDT) In-Reply-To: X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Xref: csiph.com comp.lang.python:106170 On Thu, Mar 31, 2016 at 9:24 AM, Peter Otten <__peter__@web.de> wrote: > But note: > >>>> def get(seq, index, default=None): > ... return (seq[index:index+1] or [default])[0] > ... >>>> get("abc", -1, "default") > 'default' The discontinuity between -1 and 0 in indexing is a pain in the rear. Negative indexes are one of those things that may seem like a good idea at first, but I think in the end it causes more trouble than it's worth. There's nothing you can do with L[-x] that you can't do more explicitly with L[len(L) - x].