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

arrays, ruby

Solution

You can use `sort_by` with `index`

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

order = [2,1,3]  

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

You can make it slightly faster by indexing the list of elements you want to order by:

order_with_index = order.each.with_object.with_index({}) do |(elem, memo), idx|
  memo[elem] = idx
end

then instead of `order.index(<val>)` use `order_with_index[<val>]`

Problem

I have an array of hashes in the format shown below and I am attempting to sort the `:book` 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 `Array#index` (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 `Array#sort` and `Array#sort_by` but they don't seem to accept a custom order. What am I missing? Thank you in advance for your help! Array of Hashes ``` [{:book=>"Matthew", :chapter=>"4", :section=>"new_testament"}, {:book=>"Matthew", :chapter=>"22", :section=>"new_testament"}, {:book=>"Mark", :chapter=>"6", :section=>"new_testament"}, {:book=>"1John", :chapter=>"1", :section=>"new_testament"}, {:book=>"1John", :chapter=>"1", :section=>"new_testament"}, {:book=>"Acts", :chapter=>"9", :section=>"new_testament"}, {:book=>"Acts", :chapter=>"17", :section=>"new_testament"}] ```

Original source