How to remove duplicates in a hash in Ruby on Rails?

Question

I have a hash like so:

[
  {
    :lname => \"Brown\",
    :email => \"james@intuit.com\",
    :fname => \"James\"
  },
  {
    :lname => nil,
            


        

Answer 1

Ok, this (delete duplicates) is what you asked for:

a.sort_by { |e| e[:email] }.inject([]) { |m,e| m.last.nil? ? [e] : m.last[:email] == e[:email] ? m : m << e }

But I think this (merge values) is what you want:

a.sort_by { |e| e[:email] }.inject([]) { |m,e| m.last.nil? ? [e] : m.last[:email] == e[:email] ? (m.last.merge!(e) { |k,o,n| o || n }; m) : m << e }

Perhaps I'm stretching the one-liner idea a bit unreasonably, so with different formatting and a test case:

Aiko:so ross$ cat mergedups
require 'pp'

a = [{:fname=>"James", :lname=>"Brown", :email=>"james@intuit.com"},
     {:fname=>nil,     :lname=>nil,     :email=>"brad@intuit.com"},
     {:fname=>"Brad",  :lname=>"Smith", :email=>"brad@intuit.com"},
     {:fname=>nil,     :lname=>nil,     :email=>"brad@intuit.com"},
     {:fname=>"Brad",  :lname=>"Smith", :email=>"brad@intuit.com"},
     {:fname=>"Brad",  :lname=>"Smith", :email=>"brad@intuit.com"}]

pp(
  a.sort_by { |e| e[:email] }.inject([]) do |m,e|
    m.last.nil? ? [e] :
      m.last[:email] == e[:email] ? (m.last.merge!(e) { |k,o,n| o || n }; m) :
        m << e
  end
)
Aiko:so ross$ ruby mergedups
[{:email=>"brad@intuit.com", :fname=>"Brad", :lname=>"Smith"},
 {:email=>"james@intuit.com", :fname=>"James", :lname=>"Brown"}]