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Use the inbuilt ES6 function some() to iterate through each and every element of first array and to test the array. Use the inbuilt function includes() with second array to check if element exist in the first array or not. If element exist then return true else return false.
To append one array to another, call the concat() method on the first array, passing it the second array as a parameter, e.g. const arr3 = arr1. concat(arr2) . The concat method will merge the two arrays and will return a new array.
If every element is contained within the current array (use current. indexOf(elem) !==
(cheeses & foods).empty?
As Marc-André Lafortune said in comments, & works in linear time while any? + include? will be quadratic. For larger sets of data, linear time will be faster. For small data sets, any? + include? may be faster as shown by Lee Jarvis' answer -- probably because & allocates a new Array while another solution does not and works as a simple nested loop to return a boolean.
How about Enumerable#any?
>> cheeses = %w(chedder stilton brie mozzarella feta haloumi)
=> ["chedder", "stilton", "brie", "mozzarella", "feta", "haloumi"]
>> foods = %w(pizza feta foods bread biscuits yoghurt bacon)
=> ["pizza", "feta", "foods", "bread", "biscuits", "yoghurt", "bacon"]
>> foods.any? {|food| cheeses.include?(food) }
=> true
Benchmark script:
require "benchmark"
N = 1_000_000
puts "ruby version: #{RUBY_VERSION}"
CHEESES = %w(chedder stilton brie mozzarella feta haloumi).freeze
FOODS = %w(pizza feta foods bread biscuits yoghurt bacon).freeze
Benchmark.bm(15) do |b|
b.report("&, empty?") { N.times { (FOODS & CHEESES).empty? } }
b.report("any?, include?") { N.times { FOODS.any? {|food| CHEESES.include?(food) } } }
end
Result:
ruby version: 2.1.9
user system total real
&, empty? 1.170000 0.000000 1.170000 ( 1.172507)
any?, include? 0.660000 0.000000 0.660000 ( 0.666015)
You can check if the intersection is empty.
cheeses = %w(chedder stilton brie mozzarella feta haloumi)
foods = %w(pizza feta foods bread biscuits yoghurt bacon)
foods & cheeses
=> ["feta"]
(foods & cheeses).empty?
=> false
Set.new(cheeses).disjoint? Set.new(foods)
require "benchmark"
N = 1_000_000
puts "ruby version: #{RUBY_VERSION}"
CHEESES = %w(chedder stilton brie mozzarella feta haloumi).freeze
FOODS = %w(pizza feta foods bread biscuits yoghurt bacon).freeze
Benchmark.bm(15) do |b|
b.report("&, empty?") { N.times { (FOODS & CHEESES).empty? } }
b.report("any?, include?") { N.times { FOODS.any? {|food| CHEESES.include?(food) } } }
b.report("disjoint?") { N.times { FOODS.to_set.disjoint? CHEESES.to_set }}
end
user system total real
&, empty? 0.751068 0.000571 0.751639 ( 0.752745)
any?, include? 0.408251 0.000133 0.408384 ( 0.408438)
disjoint? 11.616006 0.014806 11.630812 ( 11.637300)
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