Ruby 1.8: Hash#sort not return hash but array (bet

问题:

In some scenario of Ruby 1.8. If I have a hash

# k is name, v is order
foo = { "Jim" => 1, "bar" => 1, "joe" => 2}
sorted_by_values = foo.sort {|a, b| a[1] <==> b[1]}
#sorted_by_values is an array of array, it's no longer a hash!
sorted_by_values.keys.join ',' 

my workaround is to make method to_hash for Array class.

class Array
  def to_hash(&block)
    Hash[*self.collect { |k, v|
      [k, v]
    }.flatten]
  end
end

I can then do the following:

sorted_by_values.to_hash.keys.join ','

Is there a better way to do this?

回答1:

Hashes are unordered by definition. There can be no such thing as a sorted Hash. Your best bet is probably to extract the keys from the sorted array using collect and then do a join on the result

sortedByValues = foo.sort {|a, b| a[1] <==> b[1]}
sortedByValues.collect { |a| a[0] }.join ','