ruby-core

Issue #11076 has been updated by duerst (Martin D端rst).


sawa (Tsuyoshi Sawada) wrote:

> Since this feature is an inferior variant of `group_by` in the sense that it reduces the value arrays into their lengths, what about naming the method `group`?

Please not. The `_by` indicates that there is some specific criterion for grouping. This is the same for this method, so removing the `_by` is very strange. Also, the fact that the result contains numbers, not the actual groups, is completely lost.

Compared with this, `count_by` is much better, and so is `tally`. Other possibilities might be `group_by_and_count` or `count_by_group` or something similar.

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Feature #11076: Enumerable method count_by
https://bugs.ruby-lang.org/issues/11076#change-76636

* 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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