Source code for Point2d

    Class for creating and manipulating 2-dimensional points

import math

class Point2d(object):
[docs] def __init__(self, x0=0, y0=0): """ Method to initialize. x=0,y=0 provides default values. Example calls:: x = Point2d(5,10) x = Point2d() ## same as x = Point2d(0,0) """ self.x = x0 self.y = y0
[docs] def __str__(self): """ Method to print the object """ return '(%d, %d)' %(self.x, self.y)
[docs] def scale(self, c): """ Method to scale a point """ self.x *= c self.y *= c
[docs] def magnitude(self): """ Returns the magnitude of an object """ return math.sqrt( self.x**2 + self.y**2 )
[docs] def distance(self, other): """ Returns the distance of an object to another """ dx = self.x - other.x dy = self.y - other.y return math.sqrt ( dx**2 + dy**2 )
[docs] def grid_distance(self, other): """ Returns the grid distance between two points """ dx = self.x - other.x dy = self.y - other.y return abs(dx) + abs(dy)
[docs] def copy(self): """ Returns a new object identical to the current one. """ return Point2d(self.x, self.y)
[docs] def __add__(self, other): """ Called when adding two points: pt1 + pt2, returns a new object """ newx = self.x+other.x newy = self.y+other.y pt = Point2d(newx, newy) ## create a new object to return return pt
[docs] def __sub__(self, other): """ Called when subtracting two points: pt1 - pt2, returns a new object """ return Point2d( self.x-other.x, \ self.y-other.y )
[docs] def __eq__(self, other): """ Called when checking if two points are equal: pt1 == pt2. Returns a Boolean """ return self.x==other.x and self.y==other.y
[docs] def move(self, command): command = command.lower() if command == 'up': self.y += 1 elif command == 'down': self.y -= 1 elif command == 'left': self.x -= 1 elif command == 'right': self.x += 1
if __name__ == '__main__': ### first let us tests all the implemented methods pt1 = Point2d(5, 10) ##cals to __init__ pt2 = Point2d(10, 20) ##cals to __init__ print pt1, pt2 ##cals to __str__ pt1.scale(10) ## function that returns no value is called like this m = pt1.magnitude() ## function returns value but takes no arguments print m d = pt1.distance(pt2) ## function to find distance between two points d2 = pt2.distance(pt1) ## which returns a value print d, d2 ## the two different ways to call should be equal pt3 = pt1+pt2 ## calls __add__ print pt3 pt3 = pt1-pt2 ## calls __sub__ print pt3 pt4 = pt1.copy() print pt4 print pt4==pt1, '(True if copy works)' ## calls __eq__, they should be the same print pt1==pt2, '(should be False)' ## they should be different ## Let us use the points to solve a previous homework print print 'HW solution' pt1 = Point2d(5, 10) cmd1 = ['up','down','left'] pt2 = Point2d(15, 3) cmd2 = ['right','stay', 'down'] print "Wallace at:", pt1, "Gromit at:", pt2 for i in range(len(cmd1)): pt1.move( cmd1[i] ) pt2.move( cmd2[i] ) print pt1, pt2, pt1.grid_distance(pt2)