ruby - 处理哈希数组

给定一个类似于这样的Ruby哈希数组：

[{"lib1"=>"30"}, {"lib2"=>"30"}, {"lib9"=>"31"}, {"lib2"=>"31"}, {"lib3"=>"31"}, {"lib1"=>"32"}, {"lib2"=>"32"}, {"lib1"=>"33"}, {"lib3"=>"36"}, {"lib2"=>"36"}, {"lib1"=>"37"}]

我怎么得到这样的散列：

{"lib1"=>[30,32,33,37], lib2=>[30,31,32,36], lib3=>[31,36], lib9=>[31]}

最佳答案

a = [{"lib1"=>"30"}, {"lib2"=>"30"}, {"lib9"=>"31"}, {"lib2"=>"31"}, {"lib3"=>"31"}, {"lib1"=>"32"}, {"lib2"=>"32"}, {"lib1"=>"33"}, {"lib3"=>"36"}, {"lib2"=>"36"}, {"lib1"=>"37"}]

a.map(&:to_a).flatten(1).each_with_object({}) do |(k, v), h|
  h[k] ||= []
  h[k] << v
end
#=> {"lib1"=>["30", "32", "33", "37"],
#    "lib2"=>["30", "31", "32", "36"],
#    "lib9"=>["31"],
#    "lib3"=>["31", "36"]}

可选地：

Hash[a.map(&:to_a).flatten(1).group_by(&:first).map { |k, v| [k, v.map(&:last)] }]

如果您愿意使用Facets，那么使用collate，这将变得非常简单：

a.inject(:collate)