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logic.py
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logic.py
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class Simulation:
"""Stores environment values, initial values and executes rover instructions."""
def __init__(self, grid_x, grid_y):
"""Set the maximum coordinates of the quadrant. The intended start position and current rover position
are undefined."""
self.max_x = grid_x
self.max_y = grid_y
self.start_x = None
self.start_y = None
self.start_o = None
self.curr_x = None
self.curr_y = None
self.curr_o = None
self.verbose = False
self.obstacles = set()
def set_rover_start(self, start_x, start_y, start_orientation):
"""Set the intended start position of the rover. The current rover position is undefined."""
self.start_x = start_x
self.start_y = start_y
self.start_o = start_orientation
self.curr_x = None
self.curr_y = None
self.curr_o = None
def _set_rover_current_to_start(self):
"""Move the current rover to its start position."""
self.curr_x = self.start_x
self.curr_y = self.start_y
self.curr_o = self.start_o
def rotate(self, direction):
"""Rotate 90 degrees in given direction."""
leftward = {"N": "W", "S": "E", "E": "N", "W": "S"}
rightward = {"N": "E", "S": "W", "E": "S", "W": "N"}
rotate = {"left": leftward, "right": rightward}
self.curr_o = rotate[direction][self.curr_o]
def move(self):
"""Increment one step in current orientation, unless that moves out of bounds."""
if self.curr_o == "N":
self.curr_y = min(self.curr_y + 1, self.max_y)
elif self.curr_o == "S":
self.curr_y = max(self.curr_y - 1, 0)
elif self.curr_o == "E":
self.curr_x = min(self.curr_x + 1, self.max_x)
elif self.curr_o == "W":
self.curr_x = max(self.curr_x - 1, 0)
def print_state(self, instruction):
"""Print the state of the current rover, with the instruction that achieved it."""
print("%s: %s %s %s" % (instruction, self.curr_x, self.curr_y, self.curr_o))
def simulate(self, rover_command):
"""Follow the given commands to simulate rover movement."""
# initialise
self._set_rover_current_to_start()
if self.verbose:
self.print_state("-")
# skip simulation if start position is already an obstacle
start = (self.start_x, self.start_y)
if start in self.obstacles:
self.curr_x = -1
self.curr_y = -1
self.curr_o = "O"
if self.verbose:
self.print_state("-")
return
# otherwise process instructions
for instruction in rover_command:
if instruction == "L":
self.rotate("left")
elif instruction == "R":
self.rotate("right")
elif instruction == "M":
self.move()
else:
raise ValueError("Unknown rover command.")
if self.verbose:
self.print_state(instruction)
self.obstacles.add(
(self.curr_x, self.curr_y)
) # append final position as a new obstacle