I have an array of hashes:
[{"Vegetable"=>10}, {"Vegetable"=>5}, {"Dry Goods"=>3>}, {"Dry Goods"=>2}]
I need to use inject
here I think but I've really been struggling.
I want a new hash that reflects the sum of the previous hash's duplicate keys:
[{"Vegetable"=>15}, {"Dry Goods"=>5}]
I'm in control of the code that outputs this hash so I can modify it if necessary. The results were mainly hashes because this could end up nested any number of levels deep and then it's easy to call flatten on the array but not flatten the keys/values of the hash too:
def recipe_pl(parent_percentage=nil)
ingredients.collect do |i|
recipe_total = i.recipe.recipeable.total_cost
recipe_percentage = i.ingredient_cost / recipe_total
if i.ingredientable.is_a?(Purchaseitem)
if parent_percentage.nil?
{i.ingredientable.plclass => recipe_percentage}
else
sub_percentage = recipe_percentage * parent_percentage
{i.ingredientable.plclass => sub_percentage}
end
else
i.ingredientable.recipe_pl(recipe_percentage)
end
end
end
ar = [{"Vegetable"=>10}, {"Vegetable"=>5}, {"Dry Goods"=>3}, {"Dry Goods"=>2}]
p ar.inject{|memo, el| memo.merge( el ){|k, old_v, new_v| old_v + new_v}}
#=> {"Vegetable"=>15, "Dry Goods"=>5}
Hash.merge
with a block runs the block when it finds a duplicate; inject
without a initial memo
treats the first element of the array as memo
, which is fine here.