ruby-on-rails - 将类似的数组值合并到新的分组数组？

Question

我需要按如下方式组合类似的数组值:

来自:

arr = ['abc', 'abc', 'eff', 'eff', 'foo', 'bar', 'bar', 'bar']

收件人:

merged_like_arr = [ ['abc', 'abc'], ['eff', 'eff'], ['foo'], ['bar', 'bar', 'bar']]

基本上有一个 ActiveRecord 对象，它按顺序返回记录集合。

aff=Registration.order('affiliate DESC')
aff.map{|code| code. affiliate }
  # produces the following:
  # arr = ['abc', 'abc', 'eff', 'eff', 'foo', 'bar', 'bar', 'bar']

我需要将数据形式 arr 更改为 merged_like_arr(如上所示)，以便我可以执行以下操作:

merged_like_arr.sort_by{|arr|-arr.size}.first(10)
 #=> [ ["bar", "bar", "bar"], ["eff", "eff"], ["abc", "abc"] ... ] 

目的是通过查找他们的成员(member) ID 在注册表中使用的次数，找到系统中排名前 10 位的成员(member)。

也欢迎其他实现。谢谢!

Answer 1

The purpose is to find the top 10 affiliates in the system by looking up how many times their affiliate id was used in the registration table.

您可以使用 count使用 group 进行此类查询:

If count is used with group, it returns a Hash whose keys represent the aggregated column, and the values are the respective amounts:

Person.group(:city).count
# => { 'Rome' => 5, 'Paris' => 3 }

在你的情况下:

Registration.group(:affiliate).count
#=> { 'abc' => 2, 'eff' => 2, 'foo' => 1, 'bar' => 3 }