Using gsub in array of hashes

Question

I want to remove the spaces in the key value in the hashes

output = [
  {"first name"=> "george", "country"=>"Australia"},
  {"second name"=> "williams", "country"=>"South Africa"},
  {"first name"=> "henry", "country"=>"US"}]

I was able to manage when only one hash was there inside the array with the following code

    Array.wrap({}.tap do |hash|
     output.each do |key|
      key.each do |k, v|
       hash[k.gsub(" ","_")] = v
      end
     end
    end)

Please help me to modify the array containing more than one hash.

Note: the output value is dynamic that we cannot hardcode the hash key in the code.

It worked only with [{"first name" => "George", "country" => "Australia"}] — user3636388
– user3636388, Commented Mar 31, 2016 at 14:14

Vasfed · Accepted Answer · 2016-03-31 14:16:52Z

1

If hash is not nested - you can simply

output.map{|h| h.each_pair.map{|k,v| [k.gsub(' ', '_'), v]}.to_h }

edited Mar 31, 2016 at 14:16

answered Mar 31, 2016 at 13:51

Vasfed

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3 Comments

user3636388 Over a year ago

The whole hash is array wrapped

user3636388 Over a year ago

Please note that it is an array of hashes

Cary Swoveland Over a year ago

user3636388, I expect @Vasfed realized that, but the essence of the question is how to "remove spaces" in a hash's keys. Once you know how to do it for one hash, you obviously would just map the array, converting each (hash) element. The question would have been better had you confined it to a single hash. You are new to Ruby, however, so it's understandable that you didn't do that.

Anthony · Accepted Answer · 2016-03-31 13:50:25Z

0

Here's code that will change the spaces to underscores for each key in a hash:

output.flat_map { |h| h.map { |key, v| { key.gsub(" ", "_") => v } } }
=> [{"first_name"=>"george"}, {"country"=>"Australia"}, {"second_name"=>"williams"}, {"country"=>"South Africa"}, {"first_name"=>"henry"}, {"country"=>"US"}]

answered Mar 31, 2016 at 13:50

Anthony

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Comments

Cary Swoveland · Accepted Answer · 2016-03-31 17:22:44Z

0

You cannot modify a hash's keys. You must remove the unwanted key and add a new one. Here's a way of doing both operations in one step (see the doc Hash#delete):

def convert(h) 
  h.keys.each { |k| (h[k.tr(' ','_')] = h.delete(k)) if k =~ /\s/ }
  h
end

Hence:

output.map { |h| convert h }
  #=> [{"country"=>"Australia", "first_name"=>"george"},
  #    {"country"=>"South Africa", "second_name"=>"williams"},
  #    {"country"=>"US", "first_name"=>"henry"}]

I've used the method String#tr to convert spaces to underscores, but you could use String#gsub as well. Also, you could write k.include?(' ') rather than k =~ /\s/.

edited Mar 31, 2016 at 17:22

answered Mar 31, 2016 at 16:55

Cary Swoveland

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