如何在 Ruby on Rails 中删除哈希中的重复项? [英] How to remove duplicates in a hash in Ruby on Rails?

问题描述

我有一个像这样的哈希:

<预><代码>[{:lname =>棕色的"，:email =>"[e-mail]",:fname =>詹姆士"},{:lname =>零，:email =>"布拉德@intuit.com",:fname =>零},{:lname =>史密斯"，:email =>"布拉德@intuit.com",:fname =>布拉德"},{:lname =>零，:email =>"布拉德@intuit.com",:fname =>零},{:lname =>史密斯"，:email =>"布拉德@intuit.com",:fname =>布拉德"},{:lname =>零，:email =>"布拉德@intuit.com",:fname =>零}]

我想学习的是如何删除重复的记录.意思是，看看有几个[e-mail]"我怎样才能删除重复的记录，这意味着删除所有其他有[e-mail]"电子邮件的人......让电子邮件成为关键而不是另一个字段?

解决方案

我知道这是一个旧线程，但 Rails 在 'Enumerable' 上有一个名为 'index_by' 的方法，在这种情况下可以很方便:

list = [{:lname =>棕色的"，:email =>"[e-mail]",:fname =>詹姆士"},{:lname =>零，:email =>"布拉德@intuit.com",:fname =>零},{:lname =>史密斯"，:email =>"布拉德@intuit.com",:fname =>布拉德"},{:lname =>零，:email =>"布拉德@intuit.com",:fname =>零},{:lname =>史密斯"，:email =>"布拉德@intuit.com",:fname =>布拉德"},{:lname =>零，:email =>"布拉德@intuit.com",:fname =>零}]

现在您可以按如下方式获取唯一行:

list.index_by {|r|r[:email]}.values

合并具有相同电子邮件 ID 的行.

list.group_by{|r|r[:email]}.map 做 |k, v|v.inject({}) { |r, h|r.merge(h){ |key, o, n|○ ||} }结尾

自定义但有效的方法:

list.inject({}) do |r, h|(r[h[:email]] ||= {}).merge!(h){ |key, old, new|老||新的 }r终值

I have a hash like so:

[
  {
    :lname => "Brown",
    :email => "[e-mail]",
    :fname => "James"
  },
  {
    :lname => nil,
    :email => "[e-mail]",
    :fname => nil
  },
  {
    :lname => "Smith",
    :email => "[e-mail]",
    :fname => "Brad"
  },
  {
    :lname => nil,
    :email => "[e-mail]",
    :fname => nil
  },
  {
    :lname => "Smith",
    :email => "[e-mail]",
    :fname => "Brad"
  },
  {
    :lname => nil,
    :email => "[e-mail]",
    :fname => nil
  }
]

What I would like to learn how to do is how to remove a record if it is duplicate. Meaning, see how there are several "[e-mail]" how can I remove the duplicate records, meaning remove all the others that have an email of "[e-mail]".... Making email the key not the other fields?

解决方案

I know this is an old thread, but Rails has a method on 'Enumerable' called 'index_by' which can be handy in this case:

list = [
  {
    :lname => "Brown",
    :email => "[e-mail]",
    :fname => "James"
  },
  {
    :lname => nil,
    :email => "[e-mail]",
    :fname => nil
  },
  {
    :lname => "Smith",
    :email => "[e-mail]",
    :fname => "Brad"
  },
  {
    :lname => nil,
    :email => "[e-mail]",
    :fname => nil
  },
  {
    :lname => "Smith",
    :email => "[e-mail]",
    :fname => "Brad"
  },
  {
    :lname => nil,
    :email => "[e-mail]",
    :fname => nil
  }
]

Now you can get the unique rows as follows:

list.index_by {|r| r[:email]}.values

To merge the rows with the same email id.

list.group_by{|r| r[:email]}.map do |k, v|
  v.inject({}) { |r, h| r.merge(h){ |key, o, n| o || n } }
end

Custom but efficient method:

list.inject({}) do |r, h| 
  (r[h[:email]] ||= {}).merge!(h){ |key, old, new| old || new }
  r
end.values

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