Question

I am a new young programmer and I am learning python. I am just making a sample program to learn how to make bigger programs.

class Robot():

    def __init__(self):
        self.xpos = 0
        self.ypos = 0

    def step(self, axis):
        print "step"
        if axis in "xX":
            self.xpos += 1
        elif axis in "yY":
            self.ypos += 1

    def walk(self, axis, steps=2):
        for i in range(steps):
            self.step(axis)

    def get_pos(self):
        print "X:%i  Y:%i" % (self.xpos, self.ypos)


robot = Robot()
robot.walk("x", steps=3)

All this does is keep track of where an individual robot is. How can i keep track if i have two robots and if they are in the same location.

Example:

robot1 = Robot()
robot2 = Robot()
robot1.walk("x",5)
robot2.walk("x",5)

they would be in the same location so how would i check to see if any robots are in the same location?

Answer 1

If you create a class like Map, it is simple to write a method that checks the location of all robots:

class Map:
    def __init__(self):
        self.robots = []

    def add_robot(self, robot):
        self.robots.add(robot)

    def is_occupied(self, x, y):
        for r in self.robots:
            if r.xpos == x and r.ypos == y:
                return True
        return False

This has the advantage of allowing many other operations you might want to perform on the map- you can tell if the path is clear, for example.

Incidentally, you might want to include a reference on each Robot a reference to the Map that it’s on (which can be set by the add_robot method, so that the robot can tell whether its movement is possible when you call its move method.