ruby-on-rails - 如果键相等，如何将哈希数组分成不同的数组？

Question

我有以下形式的哈希数组:

{"user_id"=>2, "user_name"=>"Pepo", "beneficiary_document"=>"43991028", "calification_by_qualifier"=>5.0}
{"user_id"=>2, "user_name"=>"Pepo", "beneficiary_document"=>"71730550", "calification_by_qualifier"=>3.8499999999999996}
{"user_id"=>3, "user_name"=>"Carlos", "beneficiary_document"=>"43991028", "calification_by_qualifier"=>0.0}
{"user_id"=>3, "user_name"=>"Carlos", "beneficiary_document"=>"71730550", "calification_by_qualifier"=>3.4}

基本上我想将该数组分成包含键 beneficiary_document 相同值的数组，所以对于这个例子我希望有两个数组，一个包含:

{"user_id"=>2, "user_name"=>"Pepo", "beneficiary_document"=>"43991028", "calification_by_qualifier"=>5.0}
{"user_id"=>3, "user_name"=>"Carlos", "beneficiary_document"=>"43991028", "calification_by_qualifier"=>0.0}

还有一个包含

{"user_id"=>3, "user_name"=>"Carlos", "beneficiary_document"=>"71730550", "calification_by_qualifier"=>3.4}
{"user_id"=>2, "user_name"=>"Pepo", "beneficiary_document"=>"71730550", "calification_by_qualifier"=>3.8499999999999996}

我如何授予它？

非常感谢阅读。

Answer 1

给定:

tst=[
{"user_id"=>2, "user_name"=>"Pepo", "beneficiary_document"=>"43991028", "calification_by_qualifier"=>5.0}, 
{"user_id"=>2, "user_name"=>"Pepo", "beneficiary_document"=>"71730550", "calification_by_qualifier"=>3.84},
{"user_id"=>3, "user_name"=>"Carlos", "beneficiary_document"=>"43991028", "calification_by_qualifier"=>0.0}, 
{"user_id"=>3, "user_name"=>"Carlos", "beneficiary_document"=>"71730550", "calification_by_qualifier"=>3.4}
]

您可以使用 .group_by按键获取元素的哈希值。在这种情况下，使用键 ["beneficiary_document"] 传递给 block ，您将通过该键获得数组的哈希值——在本例中为两个。

你可以这样做:

tst.group_by { |h| h["beneficiary_document"] }
# {"43991028"=>[{"user_id"=>2, "user_name"=>"Pepo", "beneficiary_document"=>"43991028", "calification_by_qualifier"=>5.0}, {"user_id"=>3, "user_name"=>"Carlos", "beneficiary_document"=>"43991028", "calification_by_qualifier"=>0.0}], "71730550"=>[{"user_id"=>2, "user_name"=>"Pepo", "beneficiary_document"=>"71730550", "calification_by_qualifier"=>3.84}, {"user_id"=>3, "user_name"=>"Carlos", "beneficiary_document"=>"71730550", "calification_by_qualifier"=>3.4}]}

要看到它打印精美:

require "pp"
PP.pp(tst.group_by {|h| h["beneficiary_document"] },$>,120)
{"43991028"=>
  [{"user_id"=>2, "user_name"=>"Pepo", "beneficiary_document"=>"43991028", "calification_by_qualifier"=>5.0},
   {"user_id"=>3, "user_name"=>"Carlos", "beneficiary_document"=>"43991028", "calification_by_qualifier"=>0.0}],
 "71730550"=>
  [{"user_id"=>2, "user_name"=>"Pepo", "beneficiary_document"=>"71730550", "calification_by_qualifier"=>3.84},
   {"user_id"=>3, "user_name"=>"Carlos", "beneficiary_document"=>"71730550", "calification_by_qualifier"=>3.4}]}

您还可以使用返回数组的散列作为 default procedure 获得相同的结果。 ，然后通过 tst 调用 .map 并通过该键将散列推送到数组中:

h=Hash.new { |h,k| h[k]=[] }
tst.map { |eh| h[eh["beneficiary_document"]].push(eh) }

或者，将其组合成一条语句:

tst.each_with_object(Hash.new { |h,k| h[k]=[] }) { |g,h|
    h[g["beneficiary_document"]].push(g)} 

所有这三种方法都会创建相同的哈希值。第一个 .group_by 是最简单的。