在哈希中查找重复键？

为了简化事情，我们假设我有下面的哈希值。

我想找到多个哈希中的键和哈希的名称。 理想情况下，我想最终结束

A is also in a A is also in b B is also in a B is also in b D is also in b D is also in c E is also in b E is also in c 

我能想到的唯一方法是：将所有键放在一个数组中，对其进行排序，删除唯一元素，搜索包含剩余数组元素的每个哈希。

我猜这有点复杂和笨拙。

题

是否有更简单的方法可以在哈希中找到重复的键？

 !/usr/bin/ruby require 'ap' a = {} b = {} c = {} a["A"] = 1 a["B"] = 1 a["C"] = 1 b["A"] = 1 b["B"] = 1 b["D"] = 1 b["E"] = 1 c["D"] = 1 c["E"] = 1 c["F"] = 1 

Answer 1

您可以构建另一个哈希来存储每个键及其哈希值：

 keys = Hash.new { |hash, key| hash[key] = [] } a.each_key { |k| keys[k] << :a } b.each_key { |k| keys[k] << :b } c.each_key { |k| keys[k] << :c } 

更确切地说， keys存储符号数组。 运行上面的代码后它看起来像这样：

 keys #=> {"A"=>[:a, :b], # "B"=>[:a, :b], # "C"=>[:a], # "D"=>[:b, :c], # "E"=>[:b, :c], # "F"=>[:c]} 

要获得预期的输出：

 keys.each do |key, hashes| next if hashes.size < 2 hashes.each { |hash| puts "#{key} is also in #{hash}" } end 

打印：

 A is also in a A is also in b B is also in a B is also in b D is also in b D is also in c E is also in b E is also in c 

Answer 2

要找到具有某个键的哈希值，您可以执行此操作。

 def find_key_in list_of_hashes, key list_of_hashes.select { |one_hash| one_hash.detect { |k,v| k == key }} end 

这样叫：

 irb(main):016:0> find_key_in [{a: 3, b: 2}, {b: 3, x: 4} ], :x => [{:b=>3, :x=>4}] 

打印哈希的名称很棘手。 看到这个问题。

Answer 3

这样的事情？

 arr = { 'a' => a, 'b' => b, 'c' =>c} #=> {"a"=>{"A"=>1, "B"=>1, "C"=>1}, "b"=>{"A"=>1, "B"=>1, "D"=>1, "E"=>1}, "c"=>{"D"=>1, "E"=>1, "F"=>1}} def my_method(letter, arr) arr.map { |el| "#{letter} is in #{el[0]}" if !el[1]["#{letter}"].nil? }.compact end 

例：

 my_method("A", arr) #=> ["A is in a", "A is in b"]