Ruby中的Hash哈希类型基本操作方法小结
1.创建哈希:就像创建数组一样,我们可以通过Hash类来创建一个Hash实例: h1 = Hash.new #默认值为nil h2 = Hash.new(“This is my first hash instance”) #默认值为” This is my first hash instance”: 上面两个例子都创建了一个空的Hash实例。一个Hash对象总是有一个默认的值――因为如果在一个Hash对象里没有找到指定的索引(key),将会返回默认值。 h2["one"] = "北京" h2["two"] = "上海" h2["three"] = "深圳" h2["four"] = "广州" Note: 如果在给Hash赋值时,使用的相同的key,那么后面的值会覆盖掉前面的值。另外,Ruby还提供了一种方便的创建和初始化Hash的方法,只需要在key后面加一个=>符号并跟一个值即可。每个key-value对用逗号隔开。然后整体用大括号括起来: h2 = { "one" => "北京","two" =>"上海","three" =>"深圳","four" =>"广州" } puts h2[“one”] #=>”北京” 如果指定的key不存在,将返回默认的值(前面有提到过)。此外,我们还可以用default方法获取默认值,用default+=方法设置默认值 puts h1.default h1.default += “This is set value method” h3 = h2 h3[“one”] = “西安” puts h h2[“one”] #=>”西安” 有的时候我们不希望上面的情况发生,即:修改了其中一个的值另一个也跟着修改了,我们可以使用clone方法make a new copy h4 = h2.clone h4[“one”] = “大连” puts h2[“one”] #=>”西安”(i.e. 值没有修改) def sorted_hash(aHash) return aHash.sort{ |a,b| a.to_s <=> b.to_s } End h1 = {1=>'one',2=>'two',3=> 'three'} h2 = {6=>'six',5=>'five',4=> 'four'} h3 = {'one'=>'A','two'=>'B','three'=>'C'} h4 = h1.merge(h2) #合并hash h5 = h1.merge(h3) def sorted_hash(aHash) return aHash.sort{|a,b| a.to_s <=> b.to_s } end p(h4) p(h4.sort) p(h5) p(sorted_hash(h5)) 结果 {5=>"five",6=>"six",1=>"one",2=>"two",3=>"three",4=>"four"} [[1,"one"],[2,"two"],[3,"three"],[4,"four"],[5,"five"],[6,"six"]] {"two"=>"B","three"=>"C","one"=>"A",3=>"three"} [[1,["one","A"],["three","C"],["two","B"]] 5.Hash类常用方法:
e.g. student = { "name" => "Steve","age" => 22,"Gender" => "male" } p student.keys #=> ["name","Gender","age"] p student.values #=> ["Steve","male",22] puts student.include?("age") #=> true puts student.size #=> 3 student.delete("Gender") puts student.has_key?("Gender") #=>false puts student.size #=>2 6.Hash的转换使用 class HashObj class << self def load_from_hash(hash) if hash.instance_of? Hash obj = HashObj.new hash.each{|k,v| obj.send :def_sget_method,k,HashObj.load_from_hash(v)} obj elsif hash.instance_of? Array hash.map{|m| HashObj.load_from_hash(m) } else hash end end end def attributes hash = {} @@reg ||= /=/ self.singleton_methods.reject{|x| @@reg =~ x.to_s}.each do |m| v = self.send(m) if v.instance_of? HashObj real_v = v.attributes elsif v.instance_of? Array real_v = [] v.each do |l| if l.instance_of? HashObj real_v << l.attributes else real_v << l end end else real_v = v end hash[m] = real_v end hash end protected def def_sget_method(name,val) self.instance_variable_set "@#{name}",val self.define_singleton_method "#{name}=" do |n_val| instance_variable_set "@#{name}",n_val end self.define_singleton_method name do instance_variable_get "@#{name}" end end end 使用demo hash = {name:'jack',age:22,phone:['61900871','8787876'],basic_info:{country:'USA',city:'New York'}} obj = HashObj.load_from_hash hash obj.name #'jack' obj.age #22 obj.phone #['61900871','8787876'] obj.basic_info #<HashObj:0x007f9eda02b360 @country="USA",@city="New York"> obj.basic_info.country #'USA' obj.attributes == hash #true obj.age = 30 obj.attributes #{:name=>"jack",:age=>30,:phone=>["61900871","8787876"],# :basic_info=>{:country=>"USA",:city=>"New York"}} (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |