From: matz@ruby.or.jp
To: ruby-core@ruby-lang.org
Subject: [ruby-core:94985] [Ruby master Feature#16155] Add an Array#intersection method
Date: Thu, 19 Sep 2019 08:31:41 +0000 (UTC) [thread overview]
Message-ID: <redmine.journal-81604.20190919083141.7383bc0f112e6fd8@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-16155.20190909045243@ruby-lang.org
Issue #16155 has been updated by matz (Yukihiro Matsumoto).
Accepted. PR welcome.
Matz.
----------------------------------------
Feature #16155: Add an Array#intersection method
https://bugs.ruby-lang.org/issues/16155#change-81604
* 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/
next prev parent reply other threads:[~2019-09-19 8:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <redmine.issue-16155.20190909045243@ruby-lang.org>
2019-09-09 4:52 ` [ruby-core:94855] [Ruby master Feature#16155] Add an Array#intersection method connor.james.shea
2019-09-09 9:40 ` [ruby-core:94857] " shevegen
2019-09-09 19:10 ` [ruby-core:94871] " connor.james.shea
2019-09-09 21:16 ` [ruby-core:94874] " matthew
2019-09-19 8:31 ` matz [this message]
2019-10-07 5:18 ` [ruby-core:95255] " sin
2019-10-07 6:57 ` [ruby-core:95257] " sin
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