Ruby从哈希获取子数据的数组

Question

我有这样的哈希：

members = { "name1" => { "country" => "country1", "city" => "city1"}, "name2" => { "country" => "country2", "city" => "city2"} }

如何通过此哈希获取一系列国家/地区：

countries = [ "country1", "country2" ]

Answer 1

require 'benchmark'

Benchmark.bm do |x|
  x.report { members.map { |_,v| v["country"] } }
  x.report { members.collect { |_,v| v["country"] } }
  x.report { members.values.map{|h| h["country"]} }
end

  user     system      total        real
0.000000   0.000000   0.000000   (  0.000014)
0.000000   0.000000   0.000000   (  0.000011)
0.000000   0.000000   0.000000   (  0.000020)

=> ["country1", "country2"]

因此，请使用members.collect { |_,v| v["country"] }，因为它是最快的。

Answer 2

 countries = members.to_a.map(&:last).map{|h| h["country"]}

我测试了它应该可以工作。