从另一个哈希中的相应值中减去哈希值

Question

我希望能够减去两个哈希并在Ruby中获得第三个哈希值.

这两个哈希看起来像这样:

h1 = {"Cat" => 100, "Dog" => 5, "Bird" => 2, "Snake" => 10}
h1.default = 0

h2 = {"cat" => 50, "dog" => 3, "BIRD" => 4, "Mouse" => 75, "Snake" => 10}
h2.default = 0

我想能够像这样在h1上调用一个方法:

h1.difference(h2)

并获得此哈希作为结果:

{"Cat" => 50, "Dog" => 2, "BIRD" => -2, "Mouse" => -75}

我想创建一个新哈希,其中包含来自两个哈希的键和新哈希的值,它们是第一个哈希中键的值减去第二个哈希中该键的值.问题是,无论密钥的情况如何,我都希望这种Hash方法能够正常工作.换句话说,我希望"猫"与"猫"相匹配.

这是我到目前为止所拥有的:

class Hash
  def difference(another_hash)
    (keys + another_hash.keys).map { |key| key.strip }.uniq.inject(Hash.new(0)) { |acc, key| acc[key] = (self[key] - another_hash[key]); acc }.delete_if { |key, value| value == 0 }
  end
end

这没关系,但不幸的是,结果并不是我想要的.

任何帮助,将不胜感激.

Answer 1

如何将哈希值转换为集合。

require 'set'

h1 = {"Cat" => 100, "Dog" => 5, "Bird" => 2, "Snake" => 10}
h1.default = 0

h2 = {"cat" => 50, "dog" => 3, "BIRD" => 4, "Mouse" => 75, "Snake" => 10}
h2.default = 0

p (h1.to_set - h2.to_set)
#=> #<Set: {["Cat", 100], ["Dog", 5], ["Bird", 2]}>