Convert array of key value object to object of the key values (ruby)

Question

I have a list of objects that have key attribute and value attribute.

I would like to convert it to an object that contains attributes named as keys with the values.

Example will make it clearer...

This

[{
    :key => "key1",
    :value => "value1"
  }, {
    :key => "key2",
    :value => "value2"
}]

Should become like this:

{
  :key1 => "value1"
  :key2 => "value2"
}

I'm sure there is one line to make it happen Thanks

falsetru · Accepted Answer · 2014-08-26 15:30:42Z

4

Using Hash::[], Array#map:

a = [{
    :key => "key1",
    :value => "value1"
  }, {
    :key => "key2",
    :value => "value2"
}]

Hash[a.map { |h| [h[:key], h[:value]] }]
# => {"key1"=>"value1", "key2"=>"value2"}

Hash[a.map { |h| h.values_at(:key, :value) }]
# => {"key1"=>"value1", "key2"=>"value2"}

Hash[a.map { |h| [h[:key].to_sym, h[:value]] }]
# => {:key1=>"value1", :key2=>"value2"}

a.each_with_object({}) {|h,g| g.update({h[:key].to_sym => h[:value]}) }
# => {:key1=>"value1", :key2=>"value2"}

edited Aug 26, 2014 at 15:30

answered Aug 26, 2014 at 14:59

falsetru

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2 Comments

Cary Swoveland Over a year ago

Here's another, ft: a.each_with_object({}) {|h,g| g.update {h[:key].to_sym => h[:value]}. +1

falsetru Over a year ago

@CarySwoveland, Thank you for the comment. I updated the answer with your solution.

fl00r · Accepted Answer · 2014-08-26 15:23:42Z

1

Hash[array.map(&:values)]
#=> {"key1"=>"value1", "key2"=>"value2"}

answered Aug 26, 2014 at 15:23

fl00r

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3 Comments

Cary Swoveland Over a year ago

The OP wants the new keys to be symbols.

fl00r Over a year ago

@CarySwoveland, ha, it won't be so elegant with symbolizing keys :)

Cary Swoveland Over a year ago

That was my suspicion. From an educational viewpoint, I think bending the question a little is OK when it permits an interesting solution. Really like your specs.

steenslag · Accepted Answer · 2014-08-26 20:35:25Z

1

Just to promote the to_h a bit:

[{
    :key => "key1",
    :value => "value1"
  }, {
    :key => "key2",
    :value => "value2"
}].map(&:values).map{|k,v| [k.to_sym,v]}.to_h

# => {:key1=>"value1", :key2=>"value2"}

answered Aug 26, 2014 at 20:35

steenslag

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