在定义的类中使用方法

Question

我正在尝试制作一个脚本，我应该制作一个类Dot，它需要X位置，Y位置和Color。我已经让班级和所有的方法都一起去了。我遇到的问题是如何应用该方法。这是我做了什么：

class Dot: 
    '''A class that stores information about a dot on a flat grid 
     attributes: X (int) Y (int), C (str)''' 

    def __init__(self, xposition, yposition, color): 
     '''xposition represents the x cooridinate, yposition represents 
      y coordinate and color represent the color of the dot''' 
     self.X = xposition 
     self.Y = yposition 
     self.C = color 


    def __str__(self): 
     "Creates a string for appropiate display to represent a point" 
     return str(self.X) + " " + str(self.Y) + " " + str(self.C) 

    def move_up(self,number): 
     '''Takes an integer and modifies the point by adding the given 
      number to the x-coordinate 
      attributes: number (int)''' 

     self.Y = number + self.Y 

    def move_right(self,number): 
     '''Takes an integer and modifies the Point by adding the given number to the y-coordinate 
      attributes: number (int)''' 

     self.X = number + self.X 

    def distance_to(point2): 
     '''Takes another Dot and returns the distance to that second Dot 
      attributes: X (int) Y (int)''' 

     distance = ((self.X - point2.X)**2) + ((self.Y - point2.Y)**2) 
     real_distance = distance.sqrt(2) 

     return real_distance 



point1 = (2,3,"red") 
print("Creates a" + " " + str(point1[2]) + " " + "dot with coordinates (" + str(point1[0]) + "," + str(point1[1]) + ")") 
point2 = (1,2,"blue") 
print("Creates a" + " " + str(point2[2]) + " " + "dot with coordinates (" + str(point2[0]) + "," + str(point2[1]) + ")") 
new_point = point1.move_up(3) 
print("Moves point up three on the y axis") 

这里是返回什么：

AttributeError: 'tuple' object has no attribute 'move_up' 

Answer 1

你永远不会实例化一个Dot对象，创建具有三个元素的元组。将其更改为：

point1 = Dot(2,3,"red") 
point2 = Dot(1,2,"blue") 

和替代

print("Creates a" + " " + str(point1[2]) + " " + "dot with coordinates (" + str(point1[0]) + "," + str(point1[1]) + ")") 

使用

print "Creates a" + " " + point1.C + " " + "dot with coordinates (" + str(point1.X) + "," + str(point1.Y) + ")" 

顺便说一句，在.format()语法更加清晰：

print "Creates a {0} dot with coordinates ({1}, {2})".format(point1.C, point1.X, point1.Y) 

Answer 2

您的代码：

point1 = (2,3,"red") 

不会创建您的Dot类的实例 - 它只会创建一个tuple。

要创建一个点，你必须调用构造函数（__init__），即：

point1 = Dot(2,3,"red")