Ruby – Create a hash from an array of keys

arrayshashruby

I have looked at other questions in SO and did not find an answer for my specific problem.

I have an array:

a = ["a", "b", "c", "d"]

I want to convert this array to a hash where the array elements become the keys in the hash and all they the same value say 1. i.e hash should be:

{"a" => 1, "b" => 1, "c" => 1, "d" => 1}

My solution, one among the others :-)

a = ["a", "b", "c", "d"]
h = Hash[a.map {|x| [x, 1]}]

new ArrayList<>(Arrays.asList(array));

Modern browsers have Array#includes, which does exactly that and is widely supported by everyone except IE:

console.log(['joe', 'jane', 'mary'].includes('jane')); //true

You can also use Array#indexOf, which is less direct, but doesn't require polyfills for outdated browsers.

console.log(['joe', 'jane', 'mary'].indexOf('jane') >= 0); //true

Many frameworks also offer similar methods:

Notice that some frameworks implement this as a function, while others add the function to the array prototype.