CODEWITHSUNDEEP
ruby-on-railsrubyarraysdata-structureshash
underScorePassionFruit
underScorePassionFruit

Reputation: 325

sort ruby hash according to predefined keys

I want to sort my ruby hash. My data comes in the following way

{"imp"=>"116", "ctr"=>"0.08", "ins"=>"7.8", "vis"=>"44"}

I'd like to prepare it the following way

{"imp"=>"116", "vis"=>"44", "ctr"=>"0.08", "ins"=>"7.8"}

what is the easiest approach to this?

Upvotes: 0

Views: 137

Answers (2)

falsetru
falsetru

Reputation: 369074

Making a mapping keys to orders could be a solution:

predefined_orders = ["imp", "vis", "ctr", "ins"]
orders = Hash[predefined_orders.each_with_index.to_a]
# => {"imp"=>0, "vis"=>1, "ctr"=>2, "ins"=>3}

h = {"imp"=>"116", "ctr"=>"0.08", "ins"=>"7.8", "vis"=>"44"}
Hash[h.sort_by { |x| orders[x[0]] }]
# => {"imp"=>"116", "vis"=>"44", "ctr"=>"0.08", "ins"=>"7.8"}

h.sort_by { |x| orders[x[0]] }.to_h  # Ruby 2.1+
# => {"imp"=>"116", "vis"=>"44", "ctr"=>"0.08", "ins"=>"7.8"}

h = {"imp"=>"116", "ctr"=>"0.08", "vis"=>"44"}
Hash[h.sort_by { |x| orders[x[0]] }]
# => {"imp"=>"116", "vis"=>"44", "ctr"=>"0.08"}

Upvotes: 1

Cary Swoveland
Cary Swoveland

Reputation: 110685

Here are two ways to do it.

h = {"imp"=>"116", "ctr"=>"0.08", "ins"=>"7.8", "vis"=>"44"}

key_order = ["imp", "vis", "ctr", "ins"]

#1

Hash[key_order.map { |k| [k, h[k]] }] 
  #=> {"imp"=>"116", "vis"=>"44", "ctr"=>"0.08", "ins"=>"7.8"}

or with Ruby 2.1

key_order.map { |k| [k, h[k]] }.to_h

#2

Hash[key_order.zip(h.values_at(*key_order))]
  #=> {"imp"=>"116", "vis"=>"44", "ctr"=>"0.08", "ins"=>"7.8"}

Here are the steps:

a = h.values_at(*key_order)
  #=> h.values_at(*["imp", "vis", "ctr", "ins"])
  #=> h.values_at("imp", "vis", "ctr", "ins")
  #=> ["116", "44", "0.08", "7.8"]

b = key_order.zip(a)
  #=> ["imp", "vis", "ctr", "ins"].zip(["116", "44", "0.08", "7.8"])
  #=> [["imp", "116"], ["vis", "44"], ["ctr", "0.08"], ["ins", "7.8"]]

Hash[b]
  #=> {"imp"=>"116", "vis"=>"44", "ctr"=>"0.08", "ins"=>"7.8"}

Upvotes: 4

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