[ruby-core:91314] [Ruby trunk Feature#11076] Enumerable method count_by

From: nobu@...
Date: 2019-01-29 02:52:41 UTC
List: ruby-core #91314
Issue #11076 has been updated by nobu (Nobuyoshi Nakada).


https://github.com/nobu/ruby/pull/new/feature/11076-Enumerable%23tally

As `Hash#[]=` copies string keys, the `object_id` will be unique unless the item is frozen.

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Feature #11076: Enumerable method count_by
https://bugs.ruby-lang.org/issues/11076#change-76561

* Author: haraldb (Harald B旦ttiger)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
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I very often use `Hash[array.group_by{|x|x}.map{|x,y|[x,y.size]}]`.

Would be nice with to have a method called `count_by`:

~~~ruby
array = ['aa', 'aA', 'bb', 'cc']
p array.count_by(&:downcase) #=> {'aa'=>2,'bb'=>1,'cc'=>1}
~~~



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