Ruby change the order of hash keys

Question

I have a hash and I would like the change the key order from.

{"result"=>{"data"=>[{"Quantity"=>13, "Rate"=>17.1},
                    {"Quantity"=>29,"Rate"=>3.2}, 
                    {"Quantity"=>7, "Rate"=>3.4}]}}

To:

{"result"=>{"data"=>[{"Rate"=>17.1, "Quantity"=>13}, 
                    {"Rate"=>3.2, "Quantity"=>29}, 
                    {"Rate"=>3.4, "Quantity"=>7}]}}

that can be accessed by hash["result"]["data"]. I tried;

hash["result"]["data"][0].each_value{|v| v.replace({"Rate" => v.delete("Rate")}.merge(v))}

But it gives error:

NoMethodError (undefined method `delete' for 17.1:Float):

Why do you want to change the order of the keys? Why do you care? What do you try to achieve? — spickermann, Dec 29 '17 at 09:52

score 2 · Accepted Answer · answered Dec 29 '17 at 09:30

2

Try this,

hash["result"]["data"].each{|v| v.replace({"Rate" => v.delete("Rate")}.merge(v))}

answered Dec 29 '17 at 09:30

Kshitij

339
1
10

score 2 · Answer 2 · answered Dec 29 '17 at 09:40

2

I think their is no need to do this much of operations. I suppose data contains your whole hash then just one map and reverse of hash will resolve your problem.

data['result']['data'] = data['result']['data'].map{|v|  Hash[v.to_a.reverse]}

answered Dec 29 '17 at 09:40

Manishh

1,444
13
23

Stefan Pochmann · Answer 3 · 2017-12-29T16:18:50.557

2

Four more ways...

Reverse the order of those hash items:

hash['result']['data'].map! { |h| h.to_a.reverse.to_h }

Move "Quantity" to the end:

hash['result']['data'].each { |h| h["Quantity"] = h.delete("Quantity") }

Move the first item to the end:

hash['result']['data'].map! { |h| h.merge([h.shift].to_h) }

Force a certain given order:

keys = ["Rate", "Quantity"]
hash['result']['data'].map! { |h| keys.zip(h.values_at(*keys)).to_h }

edited Dec 29 '17 at 16:18

answered Dec 29 '17 at 15:58

Stefan Pochmann

27,593
8
44
107

Hey @Stefan Pochmann! I'm using **force a certain given order**. It maps integer values correctly but converting strings into nil. Can you help me how can I fix this? – Ekta Garg May 17 '19 at 08:15

score 0 · Answer 4 · answered Dec 09 '22 at 11:55

0

hash = {a: 1, b: 2, c: 3}
hash.slice!(:b, :a)
puts hash # { :b => 2, :a => 1 }

answered Dec 09 '22 at 11:55

Daniel Garmoshka

5,849
39
40

Ruby change the order of hash keys

4 Answers4