I have an array of arrays like so: [[1, "dog"], [2, "cat"], [2, "bird"], [3, "monkey"]]. I want to check whether the larger array contains arrays of a given number without regard to the animal element of the array. I also do not want to loop through the array because this would become computationally heavy.
So something like @boolean = bigArray.include?([2, *]), except something that actually works...
You have two possible solutions. Detect the element in the array or convert the array into a Hash
1. Use Enumerable#detect, it will stop as soon as it finds a match and return it, nil otherwise.
> a = [[1, "dog"], [2, "cat"], [2, "bird"], [3, "monkey"]]
=> [[1, "dog"], [2, "cat"], [2, "bird"], [3, "monkey"]]
> a.detect{ |(n, _)| n == 2 }
=> [2, "cat"]
> a.detect{ |(n, _)| n == 10 }
=> nil
If you want to add this to the Array class like your example, and force it to return a boolean, do this:
class Array
def custom_include?(num)
!!detect{ |(n, _)| num == n }
end
end
Example:
> a.custom_include?(2)
=> true
> a.custom_include?(10)
=> false
2. If you don't care about the colliding keys, you could convert the array into a Hash and see if the key exists.
> a = [[1, "dog"], [2, "cat"], [2, "bird"], [3, "monkey"]]
=> [[1, "dog"], [2, "cat"], [2, "bird"], [3, "monkey"]]
> Hash[a][2]
=> "bird"
> Hash[a][10]
=> nil
One very simple way that doesn't involve looping is to convert the structure to a hash. Your arrays happen to be in an ideal format for this:
values = [[1, "dog"], [2, "cat"], [2, "bird"], [3, "monkey"]]
Hash[values][2] # "bird"
You will lose the first value for each key, but it will serve to show whether a key exists.
We can use this:
arr = [[1, "dog"], [2, "cat"], [2, "bird"], [3, "monkey"]]
arr.assoc(2)
it will return [2, cat]
in array if element is not exist
arr.assoc(10)
returns nil
bigArray.include...return[2, "cat"], or should it return["cat", "bird"], or what?