From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS4713 221.184.0.0/13 X-Spam-Status: No, score=-3.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from neon.ruby-lang.org (neon.ruby-lang.org [221.186.184.75]) by dcvr.yhbt.net (Postfix) with ESMTP id B2A961F4BD for ; Mon, 7 Oct 2019 05:19:07 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 24A291208B4; Mon, 7 Oct 2019 14:18:59 +0900 (JST) Received: from xtrwkhkc.outbound-mail.sendgrid.net (xtrwkhkc.outbound-mail.sendgrid.net [167.89.16.28]) by neon.ruby-lang.org (Postfix) with ESMTPS id E52431208A0 for ; Mon, 7 Oct 2019 14:18:57 +0900 (JST) Received: by filter0105p3las1.sendgrid.net with SMTP id filter0105p3las1-24096-5D9ACAC2-17 2019-10-07 05:18:58.423310424 +0000 UTC m=+296681.549748714 Received: from herokuapp.com (unknown [54.158.92.1]) by ismtpd0024p1mdw1.sendgrid.net (SG) with ESMTP id jnG_S08pR_q7Tg4B_HbfXg for ; Mon, 07 Oct 2019 05:18:58.109 +0000 (UTC) Date: Mon, 07 Oct 2019 05:18:58 +0000 (UTC) From: sin@prajjwal.com Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 70842 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 16155 X-Redmine-Issue-Author: connorshea X-Redmine-Sender: prajjwal X-Mailer: Redmine X-Redmine-Host: bugs.ruby-lang.org X-Redmine-Site: Ruby Issue Tracking System X-Auto-Response-Suppress: All Auto-Submitted: auto-generated X-SG-EID: =?us-ascii?Q?lEJT7ggr225JDhUuXxKa6ajUBjSSTBMqIGVlrors3nkZrLQaYdQ9vOV2nQVirR?= =?us-ascii?Q?3aLAk4tX=2FdGzqgLKWRT598mWekLzjZiFcCHxSOi?= =?us-ascii?Q?pcFqTDsAEgQVkpWDsTnmp8TEbpss8TGXO6yDrIg?= =?us-ascii?Q?mpcL3R5Dul1gJjabkkJeOu0dnVro0vQUuqeMf5P?= =?us-ascii?Q?3Fo5zCiITr3tkyZJeVOj=2FAFAQRDFfBYdZsA=3D=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 95255 Subject: [ruby-core:95255] [Ruby master Feature#16155] Add an Array#intersection method X-BeenThere: ruby-core@ruby-lang.org X-Mailman-Version: 2.1.15 Precedence: list Reply-To: Ruby developers List-Id: Ruby developers List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ruby-core-bounces@ruby-lang.org Sender: "ruby-core" Issue #16155 has been updated by prajjwal (Prajjwal Singh). Hi all, I've added an initial implementation of this based on `Array#&` on github (https://github.com/ruby/ruby/pull/2533). One thing that stands out to me is the naming inconsistency between `rb_ary_and` and `rb_ary_intersection_multi`, and I think either could be changed to be consistent with the other. Thoughts? ---------------------------------------- Feature #16155: Add an Array#intersection method https://bugs.ruby-lang.org/issues/16155#change-81932 * Author: connorshea (Connor Shea) * Status: Open * Priority: Normal * Assignee: * Target version: ---------------------------------------- `Array#union` and `Array#difference` were added in Ruby 2.6 ([see this bug](https://bugs.ruby-lang.org/issues/14097)), but an equivalent for `&` (intersection) was not. I'd like to propose `Array#intersection`. This would essentially just be a more readable alias for `Array#&`, in the same way that `Array#|` and `Array#-` have `Array#union` and `Array#difference`. I think it'd make sense for Ruby to have a more readable name for this method :) Current syntax: ``` ruby [ 1, 1, 3, 5 ] & [ 3, 2, 1 ] #=> [ 1, 3 ] [ 'a', 'b', 'b', 'z' ] & [ 'a', 'b', 'c' ] #=> [ 'a', 'b' ] ``` What I'd like to see added: ```ruby [ 1, 1, 3, 5 ].intersection([ 3, 2, 1 ]) #=> [ 1, 3 ] [ 'a', 'b', 'b', 'z' ].intersection([ 'a', 'b', 'c' ]) #=> [ 'a', 'b' ] ``` mame asks about `intersection` [in this comment](https://bugs.ruby-lang.org/issues/14097#note-26) on the `union`/`difference` bug, but as far as I can tell it was never addressed. [`Set#intersection`](http://ruby-doc.org/stdlib-2.6.2/libdoc/set/rdoc/Set.html#method-i-intersection) already exists and is an alias for `Set#&`, so there's precedent for such a method to exist. Thanks for Ruby, I enjoy using it a lot! :) Related links: - [PR for `union`](https://github.com/ruby/ruby/pull/1747) - [PR for `difference`](https://github.com/ruby/ruby/pull/1758) - [Bug for adding `union` and `difference` methods](https://bugs.ruby-lang.org/issues/14097) -- https://bugs.ruby-lang.org/