quiz4-9.py

# ----------------
# User Instructions
#
# Write two functions, path_states and path_actions. Each of these
# functions should take a path as input. Remember that a path is a 
# list of [state, action, state, action, ... ]
# 
# path_states should return a list of the states. in a path, and 
# path_actions should return a list of the actions.

def path_states(path):
    "Return a list of states in this path."
    return [node for node in path if not node[2] in ['->','<-']]

def path_actions(path):
    "Return a list of actions in this path."
    return [node for node in path if node[2] in ['->','<-']]

def test():
    testpath = [(frozenset([1, 10]), frozenset(['light', 2, 5]), 5), # state 1
                (5, 2, '->'),                                        # action 1
                (frozenset([10, 5]), frozenset([1, 2, 'light']), 2), # state 2
                (2, 1, '->'),                                        # action 2
                (frozenset([1, 2, 10]), frozenset(['light', 5]), 5),
                (5, 5, '->'), 
                (frozenset([1, 2]), frozenset(['light', 10, 5]), 10),
                (5, 10, '->'), 
                (frozenset([1, 10, 5]), frozenset(['light', 2]), 2),
                (2, 2, '->'), 
                (frozenset([2, 5]), frozenset([1, 10, 'light']), 10),
                (10, 1, '->'), 
                (frozenset([1, 2, 5]), frozenset(['light', 10]), 10),
                (10, 10, '->'), 
                (frozenset([1, 5]), frozenset(['light', 2, 10]), 10),
                (10, 2, '->'), 
                (frozenset([2, 10]), frozenset([1, 5, 'light']), 5),
                (5, 1, '->'), 
                (frozenset([2, 10, 5]), frozenset([1, 'light']), 1),
                (1, 1, '->')]
    assert path_states(testpath) == [(frozenset([1, 10]), frozenset(['light', 2, 5]), 5), # state 1
                (frozenset([10, 5]), frozenset([1, 2, 'light']), 2), # state 2
                (frozenset([1, 2, 10]), frozenset(['light', 5]), 5),
                (frozenset([1, 2]), frozenset(['light', 10, 5]), 10),
                (frozenset([1, 10, 5]), frozenset(['light', 2]), 2),
                (frozenset([2, 5]), frozenset([1, 10, 'light']), 10),
                (frozenset([1, 2, 5]), frozenset(['light', 10]), 10),
                (frozenset([1, 5]), frozenset(['light', 2, 10]), 10),
                (frozenset([2, 10]), frozenset([1, 5, 'light']), 5),
                (frozenset([2, 10, 5]), frozenset([1, 'light']), 1)]
    assert path_actions(testpath) == [(5, 2, '->'), # action 1
                                      (2, 1, '->'), # action 2
                                      (5, 5, '->'), 
                                      (5, 10, '->'), 
                                      (2, 2, '->'), 
                                      (10, 1, '->'), 
                                      (10, 10, '->'), 
                                      (10, 2, '->'), 
                                      (5, 1, '->'), 
                                      (1, 1, '->')]
    return 'tests pass' 

print test()