Question

我正在尝试重新组织哈希，以便特定键位于开头，另一个键位于结尾。例如：

x = {:a => 123, :b => 456, :c => 789, :d => 123}
# returns => {:a=>123, :b=>456, :c=>789, :d=>123}
x.sort.reverse!
# returns => [[:d, 123], [:c, 789], [:b, 456], [:a, 123]]

如何使用c开始散列，并在排序后以b结尾？

编辑：我需要订购哈希，因为当我执行“x.each | key，object | do ...”时，我需要哈希以特定键开头

Answer 1

x = {:a => 123, :b => 456, :c => 789, :d => 123}

c, b = x.delete(:c), x.delete(:b)
Hash[[[:c, c], *x.sort.reverse, [:b, b]]]
# => {:c => 789, :d => 123, :a => 123, :b => 456}

或

c, b = x.delete(:c), x.delete(:b)
Hash[:c, c, *x.sort.reverse.flatten, :b, b]
# => {:c => 789, :d => 123, :a => 123, :b => 456}

Answer 2

不要依赖哈希秩序。获取密钥，订购密钥并循环哈希：

keys = x.keys
#sort how you need it
keys.each do |key|
  object = x[key]
  #do what you want
end

Answer 3

由于Ruby 1.9哈希保持其顺序（尽管==运算符忽略了这一点）。问题是大多数这些方法早于1.9，它们用于返回一个数组。您可以通过以下方式轻松地从配对值数组创建哈希：

x = {c: 1, d: 2, a: 3, b: 4}

x.sort.reverse
#=> [[:d, 2], [:c, 1], [:b, 4], [:a, 3]]

Hash[x.sort.reverse]
#=> {:d=>2, :c=>1, :b=>4, :a=>3}

Ruby重新组织哈希

3 个答案: