ruby - 合并和合并哈希数组

Question

我正在尝试获取这个哈希值数组...

items => [{:name=>"item a", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
 {:name=>"item b", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
 {:name=>"item a", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
 {:name=>"item b", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
 {:name=>"item c", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
 {:name=>"item d", :count=>1, :contributors=>["51db6d58bd02861e96000004"]}]

并得到如下所示的输出...

items => [{:name=>"item a", :count=>2, :contributors=>["51db6d58bd02861e96000004", "51db6d58bd02861e96000004"]},
     {:name=>"item b", :count=>2, :contributors=>["51db6d58bd02861e96000004, 51db6d58bd02861e96000004"]},
     {:name=>"item c", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
     {:name=>"item d", :count=>1, :contributors=>["51db6d58bd02861e96000004"]}]

我想按名称分组并合并计数和贡献者，如上图所示。我怎么做？ Group_by，减少？有人可以发布示例吗？

Answer 1

使用 Enumerable#group_by :

items = [
  {:name=>"item a", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
  {:name=>"item b", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
  {:name=>"item a", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
  {:name=>"item b", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
  {:name=>"item c", :count=>1, :contributors=>["51db6d58bd02861e96000004"]},
  {:name=>"item d", :count=>1, :contributors=>["51db6d58bd02861e96000004"]}
]
items.group_by { |h| h[:name] }.map { |key, hs|
  {:name => key,
   :count => hs.inject(0) { |c, h| c + h[:count] },
   :contributors => hs.map { |h| h[:contributors] }
  }
}

# => [{:name=>"item a", :count=>2,
#      :contributors=>[["51db6d58bd02861e96000004"], ["51db6d58bd02861e96000004"]]},
#     {:name=>"item b", :count=>2,
#      :contributors=>[["51db6d58bd02861e96000004"], ["51db6d58bd02861e96000004"]]},
#     {:name=>"item c", :count=>1, :contributors=>[["51db6d58bd02861e96000004"]]},
#     {:name=>"item d", :count=>1, :contributors=>[["51db6d58bd02861e96000004"]]}]