如何在哈希内检查数组中的某个值？

Question

I have a hash which holds a series of arrays with values in them:

av_hash = {9 => [2,4,6], 10 => [5,7], 11 => [2,3,7]}

how can I check for the presence of a certain number in the array value of a certain hash key?

So if I wanted for example to find out if key 11 contains the number 2 in its array, what's the best way to go about this?

Answer 1

It's super straightforward. Get the item with given key using hash[key_name] , then use Enumerable#include? to check if the array contains the element you want to find.

Answer 2

You can either test the specific key you want or iterate over each key/val pair and return the key that includes the number you're looking for:

av_hash = {9 => [2,4,6], 10 => [5,7], 11 => [2,3,7]}
search_for = 2

# see if specific key has `search_for` value in it:
av_hash[11].includes? search_for 
# returns true if key 11's array includes 2

# get keys that contain the value:
av_hash.map { |k, v| k if v.include? search_for }.compact
# returns [9, 11]