CODEWITHSUNDEEP
ruby-on-railsrubyhash
thiebo
thiebo

Reputation: 1435

ruby delete hash of hash based on identical values for different keys

I have a hash of hashes like this:

authors = {"7"=> {"id"=>"60"} , "0"=> {"id"=>"60"} , "1"=> {"id"=>"99"}, "8"=> {"id"=>"99"}, "15"=> {"id"=>"19"} }

I want to merge each hash where the id of the hash in that hash is duplicated (or remove each second hash with same hash of hash id).

In this case, I want to end up with 

authors = {"7"=> {"id"=>"60"} , "1"=> {"id"=>"99"}, "15"=> {"id"=>"19"}}

There are quite a few questions on sorting hashes of hashes, and I've been trying to get my head around this, but I don't see how to achieve this.

Upvotes: 2

Views: 56

Answers (2)

Cary Swoveland
Cary Swoveland

Reputation: 110645

Here are two ways.

#1

require 'set'

st = Set.new
authors.select { |_,v| st.add?(v) } 
  #=> {"7"=>{"id"=>"60"}, "1"=>{"id"=>"99"}, "15"=>{"id"=>"19"}}

#2

authors.reverse_each.with_object({}) { |(k,v),h| h[v] = k }.
  reverse_each.with_object({}) { |(k,v),h| h[v] = [k] }
  #=> {"7"=>[{"id"=>"60"}], "1"=>[{"id"=>"99"}], "15"=>[{"id"=>"19"}]}

or

authors.reverse_each.to_h.invert.invert.reverse_each.to_h

Upvotes: 4

Ursus
Ursus

Reputation: 30056

Try this one

authors.to_a.uniq { |item| item.last["id"] }.to_h
 => {"7"=>{"id"=>"60"}, "1"=>{"id"=>"99"}, "15"=>{"id"=>"19"}}

uniq method with a block can do the work

Upvotes: 4

Related Questions