Sorting array of hashes in ruby

Question

How can I sort array of hashes if I have pre-determined order I have an array that needs to be sorted like this :

   array =  [{:attr_name=>:phone, :attr_value=>30}, {:attr_name=>:name, :attr_value=>20}, {:attr_name=>:similarity, :attr_value=>0}, {:attr_name=>:weight, :attr_value=>50}]

and I've got a hash based on which I want it to be sorted :

pre_sorted = {
            :name => 0,
            :phone => 1,
            :weight=> 2,
            :similarity => 3
        }

After sorting my array should look like this :

[{:attr_name=>:name, :attr_value=>20}, {:attr_name=>:phone, :attr_value=>30}, {:attr_name=>:weight, :attr_value=>50}, {:attr_name=>"similarity", :attr_value=>0}]

I've looked at the ruby sort and sort by docs and found related questions on So but couldn't figure it out because I'm just starting with rails.

Answer 1

To sort an array by a given criterion, you can use sort_by . In your case you want to sort by the entry in the pre_sorted hash, so:

array.sort_by do |hash|
  pre_sorted[ hash[:attr_name] ]
end

Answer 2

Array＃sort接受用于比较的代码块： http : //www.ruby-doc.org/core-1.9.3/Array.html#method-i-sort

array.sort{|a,b| pre_sorted[a[:attr_value]] <=> pre_sorted[b[:attr_value]]}