Pattern decoding

Question

I need a little help in the following. I have this kind of datafile:

0 0    # <--- Group 1 -- 1 house (0) and 1 room (0)

0 0    # <--- Group 2 -- 2 ho         


        

Answer 1

I would first define a House class and a Group class:

class House:
    def __init__(self, rooms):
        self.rooms = rooms


class Group:
    def __init__(self, index, houses):
        self.index = index
        # houses.values() is a list with number of rooms for each house.
        self.houses = [House(houses[house_nr]) for house_nr in sorted(houses)]

    def __str__(self):
        return 'Group {}'.format(self.index)

    def __repr__(self):
        return 'Group {}'.format(self.index)

Then parse the data into this hierarchical structure:

with open('in.txt') as f:             
    groups = []

    # Variable to accumulate current group.
    group = collections.defaultdict(int)

    i = 1
    for line in f:
        if not line.strip():
            # Empty line found, create a new group.
            groups.append(Group(i, group))
            # Reset accumulator.
            group = collections.defaultdict(int)
            i += 1
            continue

        house_nr, room_nr = line.split()
        group[house_nr] += 1
    # Create the last group at EOF
    groups.append(Group(i, group))

Then you can do stuff like this:

found = filter(
    lambda g:
        len(g.houses) == 1 and # Group contains one house
        g.houses[0].rooms == 1, # First house contains one room
    groups)
print(list(found)) # Prints [Group 1, Group 5, Group 6]

found = filter(
    lambda g:
        len(g.houses) == 2 and # Group contains two houses
        g.houses[0].rooms == 3 and # First house contains three rooms
        g.houses[1].rooms == 2, # Second house contains two rooms
    groups)
print(list(found)) # Prints [Group 2]