How to combine multiple arrays into single JSON object

Question

I have three arrays:

c = ["1", "2", "3"]
d = [["x1","x2","x3"],["x4","x5","x6"], ["x7","x8","x9"]]
e = [["20","21","22"], ["23","24","25"], ["26","27","28"]]

And I want to merge them together in Ruby to get this JSON result:

[
 {"1":{ 
        "x1":"20",
        "x2":"21",
        "x3":"22"
      },
      { 
        "x4":"23",
        "x5":"24",
        "x6":"25"
      },
      { 
        "x7":"26",
        "x8":"27",
        "x9":"28"
      },
 }
]

What are x1, x2, x3? they seem like variables. Do you want their names in output hash? That seems impossible to do. May be you need to look at your problem differently — Wand Maker
– Wand Maker, Commented Jun 4, 2016 at 16:33
"I forget to surround them by quotes", then edit your question and fix them please. It's important that your examples and code be accurate. Please read "minimal reproducible example". — the Tin Man
– the Tin Man, Commented Jun 4, 2016 at 20:40
What is the purpose of "2" and "3" in c? Are then insignificant/ignored? If they're significant then how are you expecting them to be used? Your selected answer doesn't match your desired output at this point. — the Tin Man
– the Tin Man, Commented Jun 4, 2016 at 20:42

Cary Swoveland · Accepted Answer · 2016-07-28 19:33:45Z

4

c = ["1", "2", "3"]
d = [['x1','x2','x3'],['x4','x5','x6'], ['x7','x8','x9']]
e = [[20,21,22], [23,24,25], [26,27,28]]

require 'json'

pairs = d.map { |a| a.map(&:to_sym) }.zip(e).map(&:transpose)
  #=> [[[:x1, 20], [:x2, 21], [:x3, 22]],
  #    [[:x4, 23], [:x5, 24], [:x6, 25]],
  #    [[:x7, 26], [:x8, 27], [:x9, 28]]]    
c.each_with_object({}) { |s,h| h[s] = pairs.shift.to_h }.to_json
  #=> "{\"1\":{\"x1\":20,\"x2\":21,\"x3\":22},\"2\":
       {\"x4\":23,\"x5\":24,\"x6\":25},\"3\":{\"x7\":26,\"x8\":27,\"x9\":28}}"

(I broke the JSON string to two lines to avoid the need for horizontal scrolling.)

Alternatively,

pairs = [d.map { |a| a.map(&:to_sym) }, e].transpose.map(&:transpose)

edited Jul 28, 2016 at 19:33

answered Jun 4, 2016 at 15:27

Cary Swoveland

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