Ruby 获取对象键作为数组
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Ruby get object keys as array
提问by JD Isaacks
I am new to Ruby, if I have an object like this
我是 Ruby 新手，如果我有这样的对象
{"apple" => "fruit", "carrot" => "vegetable"}
How can I return an array of just the keys?
我怎样才能返回一个只有键的数组？
["apple", "carrot"]
回答by weezor
hash = {"apple" => "fruit", "carrot" => "vegetable"}
array = hash.keys #=> ["apple", "carrot"]
it's that simple
就这么简单
回答by Tigraine
An alternative way if you need something more (besides using the keysmethod):
如果您需要更多东西（除了使用该keys方法），另一种方法是：
hash = {"apple" => "fruit", "carrot" => "vegetable"}
array = hash.collect {|key,value| key }
obviously you would only do that if you want to manipulate the array while retrieving it..
显然，如果您想在检索数组时操作数组，您只会这样做..
回答by illiptic
Like taro said, keysreturns the array of keys of your Hash:
就像芋头说的，keys返回哈希的键数组：
http://ruby-doc.org/core-1.9.3/Hash.html#method-i-keys
http://ruby-doc.org/core-1.9.3/Hash.html#method-i-keys
You'll find all the different methods available for each class.
您将找到每个类可用的所有不同方法。
If you don't know what you're dealing with:
如果你不知道你在处理什么：
puts my_unknown_variable.class.to_s
This will output the class name.
这将输出类名。
回答by ridecar2
Use the keysmethod: {"apple" => "fruit", "carrot" => "vegetable"}.keys == ["apple", "carrot"]
使用keys方法：{"apple" => "fruit", "carrot" => "vegetable"}.keys == ["apple", "carrot"]
