Ruby:根据条件拆分/排序数组

Question

我有一系列假期:

Holiday.all                        
Holiday Load (0.7ms)  SELECT "holidays".* FROM "holidays"
=> #<ActiveRecord::Relation [#<Holiday id: 1, name: "Dia da Confraternização Universal", holidayable_id: 1, holidayable_type: "Country", date: "2014-01-01", created_at: "2014-11-05 21:38:13", updated_at: "2014-11-05 21:38:13", verified?: false>, #<Holiday id: 2, name: "Natal", holidayable_id: 1, holidayable_type: "Country", date: "2014-12-25", created_at: "2014-11-05 22:02:33", updated_at: "2014-11-05 22:02:33", verified?: false>]> 

我想按日期月份拆分这一大日期数组，所以我最终得到 12 个数组(每个月一个)。

Answer 1

您要使用的是 Enumerable#group_by方法。

Groups the collection by result of the block. Returns a hash where the keys are the evaluated result from the block and the values are arrays of elements in the collection that correspond to the key.

If no block is given an enumerator is returned.

(1..6).group_by { |i| i%3 }   #=> {0=>[3, 6], 1=>[1, 4], 2=>[2, 5]}

例如

["12/25", "01/01", (...)].group_by { |date| date.split("/").first }