It is just me, or does "do you read the portugese map" not really make sense in english? Not sure how it would be used?
The first case I can think of is 'Do you read the Portuguese map, or the Danish one?' ;)
'Læser du det portugisiske kort?' would be a direct translation. In English both 'the' and 'that' translate into 'det'. If you translate my sentence back into English you should therefore consider if you're speaking about 'the Portuguese map' (as opposed to a German one i.e.) or 'THAT (specific) Portuguese map' (that is old and outdated, i.e.)...
Surely "are you reading the map of Portugal " makes a bit more sense than the literal translation ? Or am i missing something ?