Kurt W Kurt W - 1 year ago 140
Ruby Question

Ruby - sort array of hashes values (string) based on array order

I have an array of hashes in the format shown below and I am attempting to sort the

key of the hash based on a separate array. The order is not alphabetical and for my use case it cannot be alphabetical.

I need to sort based on the following array:

array = ['Matthew', 'Mark', 'Acts', '1John']

Note that I've seen several solutions that leverage
(such as Sorting an Array of hashes based on an Array of sorted values) to perform a custom sort but that will not work with strings.

I've tried various combinations of sorting with
but they don't seem to accept a custom order. What am I missing? Thank you in advance for your help!

Array of Hashes


Answer Source

Here's an example

arr = [{a: 1}, {a: 3}, {a: 2}] 

order = [2,1,3]  

arr.sort { |a,b| order.index(a[:a]) <=> order.index(b[:a]) }                                           
# => [{:a=>2}, {:a=>1}, {:a=>3}]  

In your case it would be

order = ['Matthew', 'Mark', 'Acts', '1John']
result = list_of_hashes.sort do |a,b|
  order.index(a[:name]) <=> order.index(b[:name])

There are two important concepts here:

  1. Using Array#index to find where in an array an element is found
  2. the 'spaceship operator' <=> which is how Array#sort works - see What is the Ruby <=> (spaceship) operator?
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