红宝石数组。 group_by并在一行中修改

问题描述

  [{：type =>Meat，：name = >one}，
 {：type =>Meat，：name =>two}，
 {：type =>Fruit，：name => four}] 
  

我想将它转换为

  {Meat=> [one，two]，Fruit=> [Four]} 
  

我试过 group_by 然后我得到了这个

  {Meat=> [{：type =>Meat，：name =>one}，{：type =>Meat，：：name =>two}]，
Fruit > [{：type =>Fruit，：name =>four}]} 
  

然后我无法修改它只留下名称而不是完整的散列。我需要在一行中执行此操作，因为在Rails表单上的 grouped_options_for_select 。

解决方案

  array.group_by {| H | h [：type]}。each {| _，v | v.replace（v.map {| h | h [：name]}）} 
＃=> {Meat=> [one，two]，Fruit=> [four]} 
  

以下是steenslag的建议：

  array.group_by {| h | h [：type]}。each {| _，v | v.map {|！H | h [：name]}} 
＃=> {Meat=> [one，two]，Fruit=> [four]} 
  

I have an array of hashes, something like

[ {:type=>"Meat", :name=>"one"}, 
  {:type=>"Meat", :name=>"two"}, 
  {:type=>"Fruit", :name=>"four"} ]

and I want to convert it to this

{ "Meat" => ["one", "two"], "Fruit" => ["Four"]}

I tried group_by but then i got this

{ "Meat" => [{:type=>"Meat", :name=>"one"}, {:type=>"Meat", :name=>"two"}],
  "Fruit" => [{:type=>"Fruit", :name=>"four"}] }

and then I can't modify it to leave just the name and not the full hash. I need to do this in one line because is for a grouped_options_for_select on a Rails form.

解决方案

array.group_by{|h| h[:type]}.each{|_, v| v.replace(v.map{|h| h[:name]})}
# => {"Meat"=>["one", "two"], "Fruit"=>["four"]}

Following steenslag's suggestion:

array.group_by{|h| h[:type]}.each{|_, v| v.map!{|h| h[:name]}}
# => {"Meat"=>["one", "two"], "Fruit"=>["four"]}

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