Update astar.py

machine_learning/astar.py

@@ -1,41 +1,38 @@
 """
-The A* algorithm combines features of uniform-cost search and pure
-heuristic search to efficiently compute optimal solutions.
-A* algorithm is a best-first search algorithm in which the cost
-associated with a node is f(n) = g(n) + h(n),
-where g(n) is the cost of the path from the initial state to node n and
-h(n) is the heuristic estimate or the cost or a path
-from node n to a goal.A* algorithm introduces a heuristic into a
-regular graph-searching algorithm,
-essentially planning ahead at each step so a more optimal decision
-is made.A* also known as the algorithm with brains
+The A* algorithm combines features of uniform-cost search and pure heuristic search to
+efficiently compute optimal solutions.
+
+The A* algorithm is a best-first search algorithm in which the cost associated with a
+node is f(n) = g(n) + h(n), where g(n) is the cost of the path from the initial state to
+node n and h(n) is the heuristic estimate or the cost or a path from node n to a goal.
+
+The A* algorithm introduces a heuristic into a regular graph-searching algorithm,
+essentially planning ahead at each step so a more optimal decision is made. For this
+reason, A* is known as an algorithm with brains.
+
+https://en.wikipedia.org/wiki/A*_search_algorithm
 """
 import numpy as np
 
 
 class Cell:
     """
-    Class cell represents a cell in the world which have the property
-    position : The position of the represented by  tupleof x and y
-    coordinates initially set to (0,0)
-    parent : This contains the parent cell object which we visited
-    before arrinving this cell
-    g,h,f : The parameters for constructing the heuristic function
-    which can be any function. for simplicity used line
-    distance
+    Class cell represents a cell in the world which have the properties:
+    position: represented by tuple of x and y coordinates initially set to (0,0).
+    parent: Contains the parent cell object visited before we arrived at this cell.
+    g, h, f: Parameters used when calling our heuristic function.
     """
 
     def __init__(self):
         self.position = (0, 0)
         self.parent = None
-
         self.g = 0
         self.h = 0
         self.f = 0
 
     """
-    overrides equals method because otherwise cell assign will give
-    wrong results
+    Overrides equals method because otherwise cell assign will give
+    wrong results.
     """
 
     def __eq__(self, cell):
@@ -48,8 +45,8 @@ def showcell(self):
 class Gridworld:
     """
     Gridworld class represents the  external world here a grid M*M
-    matrix
-    world_size: create a numpy array with the given world_size default is 5
+    matrix.
+    world_size: create a numpy array with the given world_size default is 5.
     """
 
     def __init__(self, world_size=(5, 5)):
@@ -90,10 +87,10 @@ def get_neigbours(self, cell):
 
 def astar(world, start, goal):
     """
-    Implementation of a start algorithm
-    world : Object of the world object
-    start : Object of the cell as  start position
-    stop  : Object of the cell as goal position
+    Implementation of a start algorithm.
+    world : Object of the world object.
+    start : Object of the cell as  start position.
+    stop  : Object of the cell as goal position.
 
     >>> p = Gridworld()
     >>> start = Cell()
@@ -137,14 +134,14 @@ def astar(world, start, goal):
 
 if __name__ == "__main__":
     world = Gridworld()
-    #   stat position and Goal
+    # Start position and goal
     start = Cell()
     start.position = (0, 0)
     goal = Cell()
     goal.position = (4, 4)
     print(f"path from {start.position} to {goal.position}")
     s = astar(world, start, goal)
-    #   Just for visual reasons
+    #   Just for visual reasons.
     for i in s:
         world.w[i] = 1
     print(world.w)