具有重复值的数组的 ruby​​ 数组到散列的散列

Question

我是 ruby​​ 的新手，我很难弄清楚如何将数组的数组转换为数组哈希的哈希。

例如，假设我有:

[ [38, "s", "hum"], 
  [38, "t", "foo"], 
  [38, "t", "bar"], 
  [45, "s", "hum"], 
  [45, "t", "ram"], 
  [52, "s", "hum"], 
  [52, "t", "cat"], 
  [52, "t", "dog"]
]

我最终想要的是:

{38 => {"s" => ["hum"],
        "t" => ["foo", "bar"]
       },
 45 => {"s" => ["hum"],
        "t" => ["ram"]
       },
 52 => {"s" => ["hum"],
        "t" => ["cat", "dog"]
       }
 }

我已经尝试过 group_by 和 Hash，但它们都无法提供我想要的东西。

Answer 1

也许有更简洁的方法，但我决定直接走:

input = [ [38, "s", "hum"],
  [38, "t", "foo"],
  [38, "t", "bar"],
  [45, "s", "hum"],
  [45, "t", "ram"],
  [52, "s", "hum"],
  [52, "t", "cat"],
  [52, "t", "dog"]
]

output = {}

# I'll talk through the first iteration in the comments.

input.each do |outer_key, inner_key, value|
  # Set output[38] to a new hash, since output[38] isn't set yet.
  # If it were already set, this line would do nothing, so
  # output[38] would keep its previous data.
  output[outer_key] ||= {}

  # Set output[38]["s"] to a new array, since output[38]["s"] isn't set yet.
  # If it were already set, this line would do nothing, so
  # output[38]["s"] would keep its previous data.
  output[outer_key][inner_key] ||= []

  # Add "hum" to the array at output[38]["s"].
  output[outer_key][inner_key] << value
end

所以，你实际使用的部分，全部整理好:

output = {}

input.each do |outer_key, inner_key, value|
  output[outer_key] ||= {}
  output[outer_key][inner_key] ||= []
  output[outer_key][inner_key] << value
end