comparing array of hashes

Question

I have array of hashes [{"a" => 1, "b" => 2}, {"a"=> 3, "b" => 4}, {"a" => 5, "b" => 6}]. Now I need to compare all the hashes with each other, ie, compare 1st hash with 2nd and 3rd hash, and 2nd with 3rd hash. If anybody has any idea, please let me know!

Answer 1

Try this in your rails console :

irb(main):001:0> array = [{"a" => 1, "b" => 2}, {"a"=> 3, "b" => 4}, {"a" => 5, "b" => 6}]
irb(main):002:0> 0.upto(array.length-2) do |index|
irb(main):003:1* (index+1).upto(array.length-1) do |index2|
irb(main):004:2* puts "array[#{index}][a]-array[#{index2}][a] is : #{array[index]["a"]-array[index2]["a"]}"
irb(main):005:2> puts "array[#{index}][b]-array[#{index2}][b] is : #{array[index]["b"]-array[index2]["b"]}"
irb(main):006:2> end
irb(main):007:1> end
array[0][a]-array[1][a] is : -2
array[0][b]-array[1][b] is : -2
array[0][a]-array[2][a] is : -4
array[0][b]-array[2][b] is : -4
array[1][a]-array[2][a] is : -2
array[1][b]-array[2][b] is : -2
=> 0

And that's how you can compare them. I've used minus (-), you may want to use AND (&) then for that you have to put "&" symbol at the place of "-" else you can do whatever operation you wants to perform on it... :)

Answer 2

Rails has class Hash with diff method which returns the hash difference

{"a" => 1, "b" => 2}.diff("a"=> 3, "b" => 4) # { "a" => 1, "b" => 2 }

Look also at merge method, it could be useful in your case

Answer 3

rails has a nice little hash.diff method that can be easily ported into Ruby