dynamically create a hash in ruby -

i sure question has been asked before, research still hasn't led me conclusive answer. trying create standard key value pair in loop.

the code below iterates expected, storing last value. understand why, because overwriting delivery_hash variable each time use of =. tried using shovel operator have used arrays, didn't work.

def calculate_job_delivery_costs   delivery_hash = {}   delivery_cost_scopes.each |scope|     delivery_hash = { scope => job_delivery_costs.send(scope).inject(0) { |total, item| (total + item.cost_per_unit * item.hour_count) * item.quantity } }   end   delivery_hash end 

my desired output

"foo" => 234.32, 'bah' => 345.76, 'baz' => 33.87 

well, 1 thing stop blowing away variable, , use hash created in first place:

def calculate_job_delivery_costs   delivery_hash = {}   delivery_cost_scopes.each |scope|     delivery_hash[scope] = job_delivery_costs.send(scope).inject(0) |total, item|       (total + item.cost_per_unit * item.hour_count) * item.quantity     end   end   delivery_hash end 

or, simpler, build hash individual results:

def calculate_job_delivery_costs   delivery_hashes = delivery_cost_scopes.map |scope|     cost = job_delivery_costs.send(scope).inject(0) |total, item|       (total + item.cost_per_unit * item.hour_count) * item.quantity     end     [scope, cost]   end   hash[delivery_hashes] end