How to get hash values from array

Question

Input:-

array = [{"name"=>"id", "value"=>"123"}, 
         {"name"=>"type", "value"=>"app"}, 
         {"name"=>"codes", "value"=>"12"}, 
         {"name"=>"codes", "value"=>"345"}, 
         {"name"=>"type", "value"=>"app1"}] 

sample_hash = {}

Function:-

array.map {|f| sample_hash[f["name"]] = sample_hash[f["value"]] }

Result:-

sample_hash

 => {"id"=>"123", "type"=>"app", "codes"=>"345"}

But i need expected result should be like below:-

sample_hash

 => {"id"=>"123", "type"=>["app","app1"], "codes"=>["12", "345"]}

How can i get my expected output?

Although it's not exactly what you've asked for, it will make you hash easier and nicer to work with if you have an array even for the keys that only have one value e.g. "id" => ["123"] - that way when getting values from the hash you won't have to check if you have got back a string or an array. — mikej
– mikej, Commented Apr 7, 2015 at 8:00

Cristian Lupascu · Accepted Answer · 2015-04-07 07:55:19Z

1

You can initialize sample_hash using the new {|hash, key| block } Hash constructor to make the values in this hash be initialized to empty arrays by default. This makes it easier in the second phase, where each value in the initial data set is appended to the array of values indexed under the corresponding "name":

sample_hash = Hash.new { |h, k| h[k] = [] }
array.each { |f| sample_hash[f['name']] << f['value'] }

Try it online

answered Apr 7, 2015 at 7:55

Cristian Lupascu

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Comments

Arup Rakshit · Accepted Answer · 2015-04-07 08:01:08Z

1

@w0lf is correct. Same, but different construct.

array.each_with_object({}) do |input_hash, result_hash|
  (result_hash[input_hash['name']] ||= []) << input_hash['value']
end

answered Apr 7, 2015 at 8:01

Arup Rakshit

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Comments

jon snow · Accepted Answer · 2015-04-07 08:06:08Z

0

See this :

array.inject({}) do |ret, a| 
    ret[a['name']] = ret[a['name']] ? [ret[a['name']], a['value']] : a['value']  
    ret
end

o/p : {"id"=>"123", "type"=>["app", "app1"], "codes"=>["12", "345"]}

answered Apr 7, 2015 at 8:06

jon snow

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