From: muraken@...
Date: 2019-01-25T00:11:46+00:00
Subject: [ruby-core:91254] [Ruby trunk Feature#11076] Enumerable method	count_by

Issue #11076 has been updated by mrkn (Kenta Murata).


enumerable-statistics provides `value_counts` method.
https://github.com/mrkn/enumerable-statistics/blob/master/ext/enumerable/statistics/extension/statistics.c#L1651-L1668
 It is designed to follow pandas���s `Series.value_counts`.

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Feature #11076: Enumerable method count_by
https://bugs.ruby-lang.org/issues/11076#change-76501

* Author: haraldb (Harald B��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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