从Ruby中的对象数组中提取嵌套对象数组的快速方法是什么

I have an array of Elements, and each element has a property :image.

我有一个元素数组，每个元素都有一个属性:image。

I would like an array of :images, so whats the quickest and least expensive way to achieve this. Is it just iteration over the array and push each element into a new array, something like this:

我想要一系列的:图像，所以什么是最快和最便宜的方法来实现这一点。它是否只是对数组进行迭代并将每个元素推入一个新的数组中，就像这样:

images = []
elements.each {|element| images << element.image}

2 个解决方案

#1

You can use the Benchmark module to test these sorts of things. I ran @sepp2k's version against your original code like so:

您可以使用基准模块来测试这些类型的东西。我运行@sepp2k的版本与您的原始代码如下:

require 'benchmark'

class Element
  attr_accessor :image

  def initialize(image)
    @image = image
  end
end

elements = Array.new(500) {|index| Element.new(index)}

n = 10000

Benchmark.bm do |x|
  x.report do
    n.times do
      # Globalkeith's version
      image = []
      elements.each {|element| image << element.image}
    end
  end
  # sepp2k's version
  x.report { n.times do elements.map {|element| element.image} end }
end

The output on my machine was consistently (after more than 3 runs) very close to this:

我的机器上的输出始终(经过3次以上)非常接近这个:

   user     system      total        real
2.140000   0.000000   2.140000 (  2.143290)
1.420000   0.010000   1.430000 (  1.422651)

Thus demonstrating that map is significantly faster than manually appending to an array when the array is somewhat large and the operation is performed many times.

因此，当数组比较大，并且多次执行操作时，演示map比手工附加到数组的速度要快得多。

#2

elements.map {|element| element.image}

This should have about the same performance as your version, but is somewhat more succinct and more idiomatic.

这应该与您的版本具有相同的性能，但更简洁，更地道。

#1