Populate a hash with an array of keys and a default value in Ruby

Question

I have to write a method like so:

def populate_hash([key1, key2, key3], default_value)
  #
end

populate_hash([:apples, :oranges, :melons], 6) # { apples: 6, oranges: 6, melons: 6 }

If I was writing a method that was passing in two separate arrays (one for keys, one for values) it would be easy, but I'm unsure how to handle the default value.

Thank you.

Answer 1

Another way that might work is to use Array#product :

def populate_hash(array, default_value)
  Hash[array.product([default_value])]
end

If you are using Ruby 2.1+, you could use Array#to_h as well:

def populate_hash(array, default_value)
  array.product([default_value]).to_h
end

Answer 2

I believe the code is not much different from what you mention. Try this:

def populate_hash(a, default_value)
  result = {}
  a.each{|k| result[k] = default_value}
  return result
end

I have not added any checks to verify that a is and Array, but it is quite easy to do so.