RoR数组格式化，从二维数组哈希中删除一个集合，即使用键从数组中弹出一个特定的数组

Question

我有这样一个数组:

array_hash = [
  {
    "array_value" => 1,
    "other_values" => "whatever",
    "inner_value" => [
      {"iwantthis" => "forFirst"},
      {"iwantthis2" => "forFirst2"},
      {"iwantthis3" => "forFirst3"}
    ]
  },
  {
    "array_value" => 2,
    "other_values" => "whatever2",
    "inner_value" => [
      {"iwantthis" => "forSecond"},
      {"iwantthis2" => "forSecond2"},
      {"iwantthis3" => "forSecond3"}
    ]
  },
]

我想把"inner_value"从这个数组中弹出到另一个数组中

所以我想为inner_value创建一个单独的数组，格式如下:

inner_value_array = [
  {"iwantthis" => "forFirst"},
  {"iwantthis2" => "forFirst2"},
  {"iwantthis3" => "forFirst3"},
  {"iwantthis" => "forSecond"},
  {"iwantthis2" => "forSecond2"},
  {"iwantthis3" => "forSecond3"}
]

现在我不需要原始array_hash中的inner_value，所以它可以被删除。所以原来的array_hash应该是这样的

array_hash = [
  {
    "array_value" => 1,
    "other_values" => "whatever"
  },
  {
    "array_value" => 2,
    "other_values" => "whatever2"
  },
]

我已经试过了:

inner_value_array = array_hash.collect{|d| d["inner_value"] }

对于100个值，它工作得很好，很快，但它没有删除inner_value，虽然我并不关心它是否被删除，但这会占用无用的内存，所以有没有一种有效的方法来从array_hash中弹出inner_value ?

Answer 1

您可以使用flat_map

array_hash.flat_map{ |k| k['inner_value'] }
#=> [{"iwantthis"=>"forFirst"}, {"iwantthis2"=>"forFirst2"}, {"iwantthis3"=>"forFirst3"}, {"iwantthis"=>"forSecond"}, {"iwantthis2"=>"forSecond2"}, {"iwantthis3"=>"forSecond3"}]

Answer 2

我能想到的最短的东西:

inner_value_array = array_hash.inject([]) {|result,h| result << h.delete("inner_value") }

Answer 3

only_inner = []
array_hash.each {|h| only_inner << h.delete('inner_value') } # Remove the inner value and store in the only_inner array
only_inner.flatten # Combine all inner values