CODEWITHSUNDEEP
rubyhash
msayen
msayen

Reputation: 115

Join two Ruby hashes by keys

I have two hashes that look like this:

h1 = {key1: 'Roses are', key2: 'Violets are'}
h2 = {key1: 'Red', key2: 'Blue'}

I would like to join them by keys so that I get a hash like this:

result = {'Roses are' => 'Red', 'Violets are' => 'Blue'}

I have some code that does the trick:

result = {}
h1.each { |key, value| result[value] = h2[key] }

I wonder if there is a method in the standard lib to do this or whether this can be done with less code.

Upvotes: 0

Views: 90

Answers (2)

Stefan
Stefan

Reputation: 114138

You want a 1:1 mapping, so map would work:

h1.map { |k, v| ... }

The values from h1 become the new keys:

h1.map { |k, v| [v, ...] }

The corresponding values from h2 become the new values:

h1.map { |k, v| [v, h2[k]] }
#=> [["Roses are", "Red"], ["Violets are", "Blue"]]

And to_h converts that back into a hash:

h1.map { |k, v| [v, h2[k]] }.to_h
#=> {"Roses are"=>"Red", "Violets are"=>"Blue"}

Upvotes: 5

steenslag
steenslag

Reputation: 80065

Zip the values:

h1 = {key1: 'Roses are', key2: 'Violets are'}
h2 = {key1: 'Red', key2: 'Blue'}
result = h1.values.zip(h2.values).to_h

Upvotes: 1

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