按值排序散列哈希值（并返回散列值，而不是数组） [英] Sorting Hash of Hashes by value (and return the hash, not an array)

问题描述

我有以下哈希：

  user = {
'user'=> {
'title'=> {'weight'=> 1，....} 
'body'=> {'weight'=> 4，....} 
 .... 
 .... 
} 
} 
  

是否有可能让用户按照其子哈希的权重键排序？

我查看哈希。排序，但它看起来像它返回数组而不是我原来的散列排序。

解决方案在Ruby 1.9中， Hash es被排序，但是 Hash＃sort 仍返回 Array of 阵列秒。想象一下！它确实意味着你可以在它上面建立你自己的排序方法。

  class Hash 
 def sorted_hash（& amp ; block）
 self.class [sort（& block）]＃Hash [[[key1，value1]，[key2，value2]]] 
 end 
 end 
  

Hash es在Ruby 1.8中未排序。如果你想要兼容Ruby 1.8，你可以使用ActiveSupport的 OrderedHash 。它的行为类似于1.9 - Hash ，因此您可以在其上定义相同的 sorted_hash 方法：

  class ActiveSupport :: OrderedHash 
 def sorted_hash（&block）
 self.class [sort（& block）] 
 end 
 end 
 
 hash = ActiveSupport :: OrderedHash.new 
 hash [b] =b
 hash [a] =a
 hash＃=> {b=>b，a=>a} =>未排序
 hash.sorted_hash＃=> {a=>a，b=>b} =>排序！ 
  

您必须将 sorted_hash 方法复制到您的代码，因为它默认情况下不存在！

深度排序更新：
如果您想要排序除了哈希键以外，按如下方式将块传递给 sorted_hash 方法（假设从上面实现）：

  hash = ActiveSupport :: OrderedHash.new 
 hash [a] = {attr=> 2，...=> ...} 
 hash [b] = {attr=> 1，...=> ...} 
 
＃未分类。 
 hash 
＃=> {a=> {attr=>2，...=>...}，b=> {attr=>1 ...=>...}} 
 
＃按attr键排序。 （假设每个值都是散列本身！）
 hash.sorted_hash {| a，b | a [1] [attr] => b [1] [attr]} 
＃=> {b=> {attr=>1，...=>...}，a=> {attr=>2 ...=>...}} 
  

I have the following hash:

user = {
  'user' => {
    'title' => {'weight' => 1, .... }
    'body' => {'weight' => 4, ....}
     ....
     ....
  }
}

Is is possible to get the User sorted by the weight key of its child hashes?

I looked in the Hash.sort, but it looks like it returns array rather than my original hash sorted.

解决方案

In Ruby 1.9, Hashes are sorted, but Hash#sort still returns an Array of Arrays. Imagine that! It does imply that you can build your own sorting method on top of it.

class Hash
  def sorted_hash(&block)
    self.class[sort(&block)]   # Hash[ [[key1, value1], [key2, value2]] ]
  end
end

Hashes are unsorted in Ruby 1.8. If you want Ruby 1.8 compatibility, you can use ActiveSupport's OrderedHash. It behaves like a 1.9-Hash, so you can define the same sorted_hash method on it:

class ActiveSupport::OrderedHash
  def sorted_hash(&block)
    self.class[sort(&block)]
  end
end

hash = ActiveSupport::OrderedHash.new
hash["b"] = "b"
hash["a"] = "a"
hash               #=> {"b"=>"b", "a"=>"a"}  => unsorted
hash.sorted_hash   #=> {"a"=>"a", "b"=>"b"}  => sorted!

You have to copy the sorted_hash method to your code, because it does not exist by default!

Update for deep sorting: If you're looking to sort on something else than the hash key, pass a block to the sorted_hash method as follows (assuming the implementation from above):

hash = ActiveSupport::OrderedHash.new
hash["a"] = { "attr" => "2", "..." => "..." }
hash["b"] = { "attr" => "1", "..." => "..." }

# Unsorted.
hash 
  #=> {"a"=>{"attr"=>"2", "..."=>"..."}, "b"=>{"attr"=>"1", "..."=>"..."}}

# Sort on the "attr" key. (Assuming every value is a Hash itself!)
hash.sorted_hash { |a, b| a[1]["attr"] <=> b[1]["attr"] }
  #=> {"b"=>{"attr"=>"1", "..."=>"..."}, "a"=>{"attr"=>"2", "..."=>"..."}}

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