Ruby - mapping an array to hashmap

ruby hashmap
Ji Mun picture Ji Mun · Oct 22, 2012 · Viewed 62.1k times · Source

I have an array, and a function that returns a value given a value. Ultimately I want to create a hashmap that has the values of the array as key value, and the result of f(key_value) as the value. Is there a clean, simple way, like similar to each/map of Array, of doing this using block?

So something that is equivalent to

hsh = {}
[1,2,3,4].each do |x|
  hsh[x] = f(x)
end

but looks more similar to this, in that it's simple and one line? 

results = array.map { | x | f(x) }

Answer

Knotty66 picture Knotty66 · Jun 17, 2015

Note that since Ruby 2.1.0 you can also use Array#to_h, like this:

[1,2,3,4].map{ |x| [x, f(x)] }.to_h

Related questions

How to remove a key from Hash and get the remaining hash in Ruby/Rails?

To add a new pair to Hash I do: {:a => 1, :b => 2}.merge!({:c => 3}) #=> {:a => 1, :b => 2, :c => 3} Is there a similar way to delete a key from Hash ? This works: {:a => 1, :b => 2}.…

Read More
How to convert a ruby hash object to JSON?

How to convert a ruby hash object to JSON? So I am trying this example below & it doesn't work? I was looking at the RubyDoc and obviously Hash object doesn't have a to_json method. But I am reading …

Read More
Array to Hash Ruby

Okay so here's the deal, I've been googling for ages to find a solution to this and while there are many out there, they don't seem to do the job I'm looking for. Basically I have an array structured like …

Read More