Question

我对如何格式化这个对象数组感到有点迷茫。

初始数组：

cars = [{model: 'nissan', type: 'wingroad'},{model: 'nissan', type: 'sunny'},{model: 'nissan', type: 'terrano'},{model: 'toyota', type: 'hilux'}]

预期产出：

formatted_cars = [{name: 'nissan', value: ['wingroad', 'sunny', 'terrano']}, {name: 'toyota', value: ['hilux']

我是否会映射结果并应用注入然后对该格式化数组应用一些狡猾的合并技术。或者还有另一种方法吗？

我是ruby的新手，非常乐意帮助，谢谢：）

Answer 1

有很多方法可以做到这一点。这是一个;

cars = [
  {model: 'nissan', type: 'wingroad'},
  {model: 'nissan', type: 'sunny'},
  {model: 'nissan', type: 'terrano'},
  {model: 'toyota', type: 'hilux'}
]

cars
  .group_by { |car| car[:model] }
  .map { |model, cars| {name: model, value: cars.map { |car| car[:type] }} }

...但是，你为什么要从这种奇怪的数据格式开始，并试图用另一种奇怪的数据格式完成？（“奇怪”，我基本上是指依靠数组哈希数组来存储数据。）

可能是一个很好的理由（例如与第三方API集成），但我建议以某种方式使其更加面向对象并使用类来定义make / model汽车。例如，可能是：

# e.g. Nissan
class CarMake
  attr_reader :name, :models
  def initialize(name)
    @name = name
    @models = []
  end

  def add_model(name)
    model = CarModel.new(name)
    @models << model
    model.make = self
  end
end

# e.g. WingRoad
class CarModel
  attr_reader :name
  attr_accessor :make
  def initialize(name)
    @name = name
  end
end

# Assuming we still need to start with this data structure!
cars = [
  {model: 'nissan', type: 'wingroad'},
  {model: 'nissan', type: 'sunny'},
  {model: 'nissan', type: 'terrano'},
  {model: 'toyota', type: 'hilux'}
]

car_makes = {}
cars.each do |car|
  car_makes[car[:model]] ||= CarMake.new(car[:model])
  car_makes[car[:model]].add_model(car[:type])
end

这只是组织代码的许多可能方法之一，虽然最初理解起来可能有点复杂，但结果数据结构更有用：

car_makes
=> {"nissan"=>
  #<CarMake:0x00007ff2ee44ad20
   @models=
    [#<CarModel:0x00007ff2ee44aca8 @make=#<CarMake:0x00007ff2ee44ad20 ...>, @name="wingroad">,
     #<CarModel:0x00007ff2ee44ac80 @make=#<CarMake:0x00007ff2ee44ad20 ...>, @name="sunny">,
     #<CarModel:0x00007ff2ee44ac58 @make=#<CarMake:0x00007ff2ee44ad20 ...>, @name="terrano">],
   @name="nissan">,
 "toyota"=>#<CarMake:0x00007ff2ee44ac30 @models=[#<CarModel:0x00007ff2ee44ab68 @make=#<CarMake:0x00007ff2ee44ac30 ...>, @name="hilux">], @name="toyota">}

car_makes['nissan'].models
=> [#<CarModel:0x00007ff2ee44aca8 @make=#<CarMake:0x00007ff2ee44ad20 @models=[...], @name="nissan">, @name="wingroad">,
 #<CarModel:0x00007ff2ee44ac80 @make=#<CarMake:0x00007ff2ee44ad20 @models=[...], @name="nissan">, @name="sunny">,
 #<CarModel:0x00007ff2ee44ac58 @make=#<CarMake:0x00007ff2ee44ad20 @models=[...], @name="nissan">, @name="terrano">]

car_makes['nissan'].models.first
=> #<CarModel:0x00007ff2ee44aca8
 @make=
  #<CarMake:0x00007ff2ee44ad20
   @models=
    [#<CarModel:0x00007ff2ee44aca8 ...>,
     #<CarModel:0x00007ff2ee44ac80 @make=#<CarMake:0x00007ff2ee44ad20 ...>, @name="sunny">,
     #<CarModel:0x00007ff2ee44ac58 @make=#<CarMake:0x00007ff2ee44ad20 ...>, @name="terrano">],
   @name="nissan">,
 @name="wingroad">

car_makes['nissan'].models.first.make
=> #<CarMake:0x00007ff2ee44ad20
 @models=
  [#<CarModel:0x00007ff2ee44aca8 @make=#<CarMake:0x00007ff2ee44ad20 ...>, @name="wingroad">,
   #<CarModel:0x00007ff2ee44ac80 @make=#<CarMake:0x00007ff2ee44ad20 ...>, @name="sunny">,
   #<CarModel:0x00007ff2ee44ac58 @make=#<CarMake:0x00007ff2ee44ad20 ...>, @name="terrano">],
 @name="nissan">

......等等。我们现在有一个结构化数据，而不是任意（和错误命名！）混合的数组和散列操作混乱。

Answer 2

cars = [{model: 'nissan', type: 'wingroad'},
        {model: 'nissan', type: 'sunny'},
        {model: 'nissan', type: 'terrano'},
        {model: 'toyota', type: 'hilux'}]

cars.each_with_object({}) { |g,h| (h[g[:model]] ||= []) << g[:type] }.
     map { |k,v| { model:k, type:v } }
  #=> [{:model=>"nissan", :type=>["wingroad", "sunny", "terrano"]},
  #    {:model=>"toyota", :type=>["hilux"]}]

请注意

cars.each_with_object({}) { |g,h| (h[g[:model]] ||= []) << g[:type] }
  #=> {"nissan"=>["wingroad", "sunny", "terrano"], "toyota"=>["hilux"]}

Answer 3

是的，有以下内容：

cars.group_by{|h| h[:model]}.transform_values{|v| v.map{|h| h[:type]}}
#=> {"nissan"=>["wingroad", "sunny", "terrano"], "toyota"=>["hilux"]}

如何使用ruby格式化对象数组？

3 个答案: