scala - Transform a list to a map -

i have following types:

case class category(id: int, name: string) case class product(id: int, location: location, categoryidlist: option[list[int]]) 

given list of products

val products:list[product] = loadproducts() 

how can product map of categoryid location?

map[categoryid, location] 

so method this:

def getmap(products: list[product]): map[int, location] = {    ?? } 

i need somehow iterate on optional list of categoryidlist , create map location property.

in order convert seq map need first convert seq[(int,location)], seq of tuple2. tomap method available.

edit: okay here's implementation based on each categoryid on list, note shouldn't use option of list, since empty state list empty list.

def getmap(products: list[product]): map[int, location] = {    products.flatmap(tolisttuple2).tomap }   def tolisttuple2(product: product): list[(int, location)] = {   product.categoryidlist     .getorelse(list())     .map(category => (category, product.location)) } 

so here first turn our product list of categoryids , locations , flatmap list of (int, location), can turned map calling tomap.