添加一对新的哈希,我做:

{:a => 1, :b => 2}.merge!({:c => 3})   #=> {:a => 1, :b => 2, :c => 3}

是否有类似的方法从哈希中删除键?

如此:

{:a => 1, :b => 2}.reject! { |k| k == :a }   #=> {:b => 2}

但我希望有这样的东西:

{:a => 1, :b => 2}.delete!(:a)   #=> {:b => 2}

重要的是,返回值将是剩余的散列,所以我可以这样做:

foo(my_hash.reject! { |k| k == my_key })

在一行里。


当前回答

如果你正在使用Ruby 2,你可以使用改进,而不是猴子补丁或不必要地包括大型库:

module HashExtensions
  refine Hash do
    def except!(*candidates)
      candidates.each { |candidate| delete(candidate) }
      self
    end

    def except(*candidates)
      dup.remove!(candidates)
    end
  end
end

您可以在不影响程序其他部分的情况下使用此特性,也不必包含大型外部库。

class FabulousCode
  using HashExtensions

  def incredible_stuff
    delightful_hash.except(:not_fabulous_key)
  end
end

其他回答

在哈希中删除键的多种方法。 你可以使用下面的任何方法

hash = {a: 1, b: 2, c: 3}
hash.except!(:a) # Will remove *a* and return HASH
hash # Output :- {b: 2, c: 3}

hash = {a: 1, b: 2, c: 3}
hash.delete(:a) # will remove *a* and return 1 if *a* not present than return nil

有很多方法,你可以看看Ruby doc of Hash。

谢谢你!

有许多方法可以从散列中删除键并在Ruby中获取剩余的散列。

.slice => It will return selected keys and not delete them from the original hash. Use slice! if you want to remove the keys permanently else use simple slice. 2.2.2 :074 > hash = {"one"=>1, "two"=>2, "three"=>3} => {"one"=>1, "two"=>2, "three"=>3} 2.2.2 :075 > hash.slice("one","two") => {"one"=>1, "two"=>2} 2.2.2 :076 > hash => {"one"=>1, "two"=>2, "three"=>3} .delete => It will delete the selected keys from the original hash(it can accept only one key and not more than one). 2.2.2 :094 > hash = {"one"=>1, "two"=>2, "three"=>3} => {"one"=>1, "two"=>2, "three"=>3} 2.2.2 :095 > hash.delete("one") => 1 2.2.2 :096 > hash => {"two"=>2, "three"=>3} .except => It will return the remaining keys but not delete anything from the original hash. Use except! if you want to remove the keys permanently else use simple except. 2.2.2 :097 > hash = {"one"=>1, "two"=>2, "three"=>3} => {"one"=>1, "two"=>2, "three"=>3} 2.2.2 :098 > hash.except("one","two") => {"three"=>3} 2.2.2 :099 > hash => {"one"=>1, "two"=>2, "three"=>3} .delete_if => In case you need to remove a key based on a value. It will obviously remove the matching keys from the original hash. 2.2.2 :115 > hash = {"one"=>1, "two"=>2, "three"=>3, "one_again"=>1} => {"one"=>1, "two"=>2, "three"=>3, "one_again"=>1} 2.2.2 :116 > value = 1 => 1 2.2.2 :117 > hash.delete_if { |k,v| v == value } => {"two"=>2, "three"=>3} 2.2.2 :118 > hash => {"two"=>2, "three"=>3} .compact => It is used to remove all nil values from the hash. Use compact! if you want to remove the nil values permanently else use simple compact. 2.2.2 :119 > hash = {"one"=>1, "two"=>2, "three"=>3, "nothing"=>nil, "no_value"=>nil} => {"one"=>1, "two"=>2, "three"=>3, "nothing"=>nil, "no_value"=>nil} 2.2.2 :120 > hash.compact => {"one"=>1, "two"=>2, "three"=>3}

基于Ruby 2.2.2的结果。

在纯Ruby中:

{:a => 1, :b => 2}.tap{|x| x.delete(:a)}   # => {:b=>2}

这也可以工作:hash[hey] = nil

参见Ruby on Rails:删除多个散列键

hash.delete_if{ |k,| keys_to_delete.include? k }