initial commit

pig_lite/problem/base.py

@@ -0,0 +1,92 @@
+import hashlib
+
+class Node(object):
+    def __init__(self, parent, state, action, cost, depth):
+        self.parent = parent
+        self.state = state
+        self.action = action
+        self.cost = cost
+        self.depth = depth
+
+    def key(self):
+        # if state is composed of other stuff (dict, set, ...)
+        # make it a tuple containing hashable datatypes
+        # (this is supposed to be overridden by subclasses)
+        return self.state
+
+    def __hash__(self):
+        return hash(self.key())
+
+    def __eq__(self, other):
+        if type(self) == type(other):
+            return self.key() == other.key()
+        raise ValueError('cannot simply compare two different node types')
+
+    def __str__(self):
+        return self.__repr__()
+
+    def __repr__(self):
+        return 'Node(id:{}, parent:{}, state:{}, action:{}, cost:{}, depth:{})'.format(
+            id(self),
+            id(self.parent),
+            self.state,
+            self.action,
+            self.cost,
+            self.depth
+        )
+
+    def get_action_sequence(self):
+        current = self
+        reverse_sequence = []
+        while current.parent is not None:
+            reverse_sequence.append(current.action)
+            current = current.parent
+        return list(reversed(reverse_sequence))
+    
+    def get_action_sequence_hash(self):
+        action_sequence = self.get_action_sequence()
+        action_sequence_as_str = ','.join(map(str, action_sequence))
+        action_sequence_hash = hashlib.sha256(action_sequence_as_str.encode('UTF-8')).hexdigest() # should solution node return hashcode?
+        return action_sequence_hash
+    
+    def pretty_print(self):
+        print(f"state {self.state} was reached following the sequence {self.get_action_sequence()} (cost: {self.cost}, depth: {self.depth})")
+
+
+class Problem(object):
+    def get_number_of_expanded_nodes(self):
+        raise NotImplementedError()
+
+    def get_start_node(self):
+        raise NotImplementedError()
+
+    def get_end_node(self):
+        raise NotImplementedError()
+
+    def is_end(self, node):
+        raise NotImplementedError()
+
+    def action_cost(self, state, action):
+        raise NotImplementedError()
+
+    def successors(self, node):
+        raise NotImplementedError()
+
+    def to_json(self):
+        raise NotImplementedError()
+    
+    def visualize(self, **kwargs):
+        raise NotImplementedError()
+    
+    def get_action_sequence(self, end: Node):
+        if end is None:
+            return list()
+        return end.get_action_sequence()
+
+    @staticmethod
+    def from_json(jsonstring):
+        raise NotImplementedError()
+
+    @staticmethod
+    def get_minimum_problem_size():
+        raise NotImplementedError()