Ruby Array Elements Merging

Question

just wondering if there're other alternatives to merging elements in an array from

[ ["time","Oct-1-2016"], ["message","test message"], ["host","localhost"] ]

to

["time=Oct-1-2016","message=test message","host=localhost"]

I've got it nailed down toarray.map {|k,v| "#{k}=#{v}"} and just wondering if there are any other ways of achieving the above without using the map function? Thanks yo!

Still using map you can do: arr.map {|s| s.join('=')} as well. — Sagar Pandya
– Sagar Pandya, Commented Sep 23, 2016 at 2:43
Yea, I definitely overcooked the k,v portion - thanks @sagarpandya82 — b1geyedeer
– b1geyedeer, Commented Sep 23, 2016 at 2:54
Of course: [ ["time","Oct-1-2016"], ["message","test message"], ["host","localhost"] ].each_with_object([]) { |a,b| b << a.join('=') }, but it is more cumbersome than simply map. — Cary Swoveland
– Cary Swoveland, Commented Sep 23, 2016 at 3:37
When you add a silly requirement like "without using the map function", you need to explain why, because the answer might be different. "I'm learning and we're not supposed to use it", "I am a Haskell survivor and those three letters standing side by side are aggravating me", "I've redefined map to always return false and I need help with gardenias holding my pacifier hostage" have wildly different responses. map is the best tool for the job; so without it you're working with a handicap. — Amadan
– Amadan, Commented Sep 23, 2016 at 3:58
If your endgame is to produce a query string, and since you've tagged this Rails, you might be interested in to_param which ActiveSupport mixes into Hash: array.to_h.to_param => "host=localhost&message=test+message&time=Oct-1-2016". Otherwise, it's completely unclear why you would impose a restriction like "without the use of map" on your question. — user229044
– user229044 ♦, Commented Sep 23, 2016 at 12:30

retgoat · Accepted Answer · 2016-09-23 03:39:36Z

2

Let's say your array is a. Then try this solution:

[1] pry(main)> a = [ ["time","Oct-1-2016"], ["message","test message"], ["host","localhost"] ]
=> [["time", "Oct-1-2016"], ["message", "test message"], ["host", "localhost"]]

[2] pry(main)> a.map{|k, v| "#{k}=#{v}"}
=> ["time=Oct-1-2016", "message=test message", "host=localhost"]

Hm, I have no idea why map isn't works for you, but here is an example with inject:

[40] pry(main)> a.inject(Array.new){|acc, el| acc << el.join("="); acc}
=> ["time=Oct-1-2016", "message=test message", "host=localhost"]

edited Sep 23, 2016 at 3:39

answered Sep 23, 2016 at 2:53

retgoat

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4 Comments

b1geyedeer Over a year ago

Thanks for the attempt @retgoat, I'm looking for alternatives other than using the map function to achieve the result in [2].

retgoat Over a year ago

@b1geyedeer I added one more example. Hope that will work for you.

b1geyedeer Over a year ago

Thanks, that's a good alternative, just for the record map works but as I've mentioned I was wondering if there are other ways to achieve the same output other than map. Sorry if I get everyone riled up.

retgoat Over a year ago

No worries mate :) I'm glad that was able to help.

Sagar Pandya · Accepted Answer · 2016-09-23 03:56:12Z

1

Here's one way using an infinite loop inside an Enumerator and by using the cycle method. Then use enum.take arr.size to get all your new elements in an array.

arr = [ ["time","Oct-1-2016"], ["message","test message"], ["host","localhost"] ]
ar  = arr.cycle

enum = Enumerator.new do |y|
  loop do
    y << ar.next.join('=')
  end
end

enum.take arr.size
#=> ["time=Oct-1-2016", "message=test message", "host=localhost"]

answered Sep 23, 2016 at 3:56

Sagar Pandya

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