Ruby - How do I sort an array based on the value of nested hash items?

Question

I have some rather complex sorting to do.

Given an array of hashes, I need to sort the hashes within the array, based on a value in a key of each hash.

For example (given in JSON format):

"instruments":[
{"id":1,"title":"Piano","token":"piano","count":13},
{"id":6,"title":"Bass Guitar","token":"bass","count":12},
{"id":11,"title":"Viola","token":"viola","count":12},
{"id":4,"title":"Synth","token":"synth","count":11},
{"id":3,"title":"Keyboard","token":"keyboard","count":9},
{"id":7,"title":"Saxophone","token":"saxophone","count":8},
{"id":12,"title":"Flute","token":"flute","count":8},
{"id":5,"title":"Drums","token":"drums","count":6},
{"id":2,"title":"Guitar","token":"guitar","count":5},
{"id":8,"title":"Violin","token":"violin","count":5},
{"id":9,"title":"Vocals","token":"vocals","count":4},
{"id":10,"title":"Cello","token":"cello","count":4}
]

This JSON is the result of a responds_with in Rails. Before it gets to that, I'd like to switch these hashes around in the array, based on the alphabetical order of the "title" key in each hash.

Here's a screenshot of a part of the JSON (in Firebug) to better illustrate what I mean:

enter image description here

Any help would be greatly appreciated.

Thanks!

spike · Accepted Answer · 2015-02-18 16:08:33Z

6

You're looking for Enumerable#sort_by.

instruments.sort_by { |x| x["title"] }

edited Feb 18, 2015 at 16:08

answered Feb 18, 2015 at 14:03

spike

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1 Comment

Michael Giovanni Pumo Over a year ago

Wow, it's that easy! Brilliant.

Khanad · Accepted Answer · 2015-02-18 14:23:26Z

You can use the ruby sort_by method (http://ruby-doc.org/core-2.2.0/Enumerable.html#method-i-sort_by)

So in your case where the instruments look like this:

instruments=[
{"id"=>1,"title"=>"Piano","token"=>"piano","count"=>13},
{"id"=>6,"title"=>"Bass Guitar","token"=>"bass","count"=>12},
{"id"=>11,"title"=>"Viola","token"=>"viola","count"=>12},
{"id"=>4,"title"=>"Synth","token"=>"synth","count"=>11},
{"id"=>3,"title"=>"Keyboard","token"=>"keyboard","count"=>9},
{"id"=>7,"title"=>"Saxophone","token"=>"saxophone","count"=>8},
{"id"=>12,"title"=>"Flute","token"=>"flute","count"=>8},
{"id"=>5,"title"=>"Drums","token"=>"drums","count"=>6},
{"id"=>2,"title"=>"Guitar","token"=>"guitar","count"=>5},
{"id"=>8,"title"=>"Violin","token"=>"violin","count"=>5},
{"id"=>9,"title"=>"Vocals","token"=>"vocals","count"=>4},
{"id"=>10,"title"=>"Cello","token"=>"cello","count"=>4}
]

You can use this to sort by the given column ("title" in your case)

 instruments.sort_by{|instrument| instrument["title"]}

Hope this Helps.

Mosaaleb · Accepted Answer · 2021-02-14 12:37:01Z

0

In case it helps anyone following on, my JSON is doubly-nested

products = [
{:product=>{:id=>866468155, :code=>"TB2", :name=>"Thunderbird 2"}},
{:product=>{:id=>805953484, :code=>"FAB1", :name=>"Rolls-Royce FAB 1"}},
{:product=>{:id=>715919491, :code=>"TB1", :name=>"Thunderbird 1"}},
{:product=>{:id=>767677594, :code=>"TB5", :name=>"Thunderbird 5"}},
]

And I was able to sort by name using,

table.sort_by! { |x| x[:product][:name]}

...note this also uses ! to sort in place, rather than creating a new Array.

edited Feb 14, 2021 at 12:37

Mosaaleb

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answered Jan 8, 2020 at 14:29

Snips

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