Ruby - Checking if one array key/value is present in another one-CodePudding

With ruby, I am trying to look from the first array key[:nb].value, if there is one similar pair in the second one.

Considerate below arrays contain thousands of elements:

arr1 = [{"nb"=>"5df54g54df", "active"=>true, "brand"=>"aisle"},{"nb"=>"5jghfj264", "active"=>false, "brand"=>"leg"},{"nb"=>"5qwercv546", "active"=>true, "brand"=>"gem"}]

arr2 = [{"nb"=>"5df54g54df", "active"=>true, "brand"=>"aisle"},{"nb"=>"5jghfj264", "active"=>false, "brand"=>"leg"}]

So far I was thinking something like that :

p (arr1.map(&:nb).find do |nb, val| arr2.map(&:nb)).include?(nb && val)

Would you have a suggestion, please?

CodePudding user response：

How about something like this? See comments below:

arr1 = [{ 'nb' => '5df54g54df', 'active' => true, 'brand' => 'aisle' }, { 'nb' => '5jghfj264', 'active' => false, 'brand' => 'leg' },
        { 'nb' => '5qwercv546', 'active' => true, 'brand' => 'gem' }]
arr2 = [{ 'nb' => '5df54g54df', 'active' => true, 'brand' => 'aisle' },
        { 'nb' => '5jghfj264', 'active' => false, 'brand' => 'leg' }]

p(
  arr1.select do |h| # Select all objects from arr1, that return true in block:
    arr2.any? { |h2| h['nb'] == h2['nb'] } #Any element from arr2 that contains equal `'nb'` keys.
  end
)

#=> [{"nb"=>"5df54g54df", "active"=>true, "brand"=>"aisle"}, {"nb"=>"5jghfj264", "active"=>false, "brand"=>"leg"}]

CodePudding user response：

require 'set'

arr2_nb_vals = arr2.each_with_object(Set.new) do |h,arr2_nb_vals|
  arr2_nb_vals << h["nb"]
end
  #=> #<Set: {"5df54g54df", "5jghfj264"}>

arr1.select { |h| arr2_nb_vals.include?(h["nb"]) }
  #=> [{"nb"=>"5df54g54df", "active"=>true, "brand"=>"aisle"},
  #    {"nb"=>"5jghfj264", "active"=>false, "brand"=>"leg"}]

By first collecting the values of h["nb"], h in arr2, into a set, the calculation arr2_nb_vals.include?(h["nb"]) is very fast, nearly independent of arr2_nb_vals.size.

That makes the computational complexity close to O(arr1.size arr2.size), as compared with O(arr1.size**2) when arr2_nb_vals.include?(h["nb"]) is replaced with arr2.include?(h["nb"]).