def generate_cards_count():
mapper = Code("""
function() {
this.winning_deck.forEach(function(c) {
emit(c.name, 1);
});
this.loosing_deck.forEach(function(c) {
emit(c.name, 1);
});
}""")
reduce = Code("""
function(key, values) {
return Array.sum(values);
}
""")
return DB.map_reduce('battle_log', mapper, reduce, 'card_count')
