Python简单的乌龟程序

Question

我在尝试完成一个 python 乌龟程序时遇到了麻烦。当我尝试输入 x 和 y 坐标以及函数的半径值时 t.drawSnowman(x = 25,y = 25,radius = 25) 程序在我输入值时行为异常。但是如果我省略上面的参数而只使用 t.drawSnowman() 程序按预期工作但我不是能够创建雪人的各种实例。

我真的很想帮助我弄清楚如何输入参数并仍然具有程序功能。

这是我的代码

import turtle

class MyTurtle(turtle.Turtle):
""""""


def __init__(self):
    """Turtle Constructor"""
    turtle.Turtle.__init__(self, shape="turtle")

def drawNose(self, x=0, y=0, radius = 15, circle_color = "black"):
    '''draw nose '''
    self.pendown()
    self.goto(-(radius) * (0.25),(radius * 6)+(radius * 4)+(radius))
    self.goto(0,(radius * 6)+(radius * 4)+(radius)+(radius * (0.25)))
    self.goto((radius) * (0.25),(radius * 6)+(radius * 4)+(radius))
    self.goto(0,(radius * 6)+(radius * 4)+(radius))
    self.penup()

def leftEye(self, x=0, y=0, radius = 15, circle_color = "black"):
    '''draw left eye'''
    self.pendown()
    self.circle(radius*(.25))
    self.penup()
def rightEye(self, x=0, y=0, radius = 15, circle_color = "black"):
    '''draw right eye'''
    self.pendown()
    self.circle(radius*(.25))
    self.penup()
def bottomOfHat(self, x=0, y=0, radius = 15, circle_color = "black"):
    ''' draw the long part of the hat at the bottom '''
    self.goto(0,(radius * 6)+(radius * 4)+(radius * 2))
    self.pendown()
    self.goto(-(radius),(radius * 6)+(radius * 4)+(radius * 2))
    self.goto(-(radius),(radius * 6)+(radius * 4)+(radius * 2)+(radius * (0.5)))
    self.goto(radius,(radius * 6)+(radius * 4)+(radius * 2)+(radius * (0.5)))
    self.goto(radius,(radius * 6)+(radius * 4)+(radius * 2))
    self.goto(0,(radius * 6)+(radius * 4)+(radius * 2))
    self.penup()

def topOfHat(self, x=0, y=0, radius = 15, circle_color = "black"):
    '''draw the top bigger part of the hat'''
    self.goto(radius*(.75),(radius * 6)+(radius * 4)+(radius * 2)+(radius * (0.5)))
    self.pendown()
    self.goto(radius*(.75),(radius * 6)+(radius * 4)+(radius * 2)+(radius * 2))
    self.goto(-(radius)*(.75),(radius * 6)+(radius * 4)+(radius * 2)+(radius * 2))
    self.goto(-(radius)*(.75),(radius * 6)+(radius * 4)+(radius * 2)+(radius * (0.5)))

def bottomCircle(self, x=0, y=0, radius = 15, circle_color = "black"):
    '''draws the bottom circle'''
    self.pendown()
    self.circle(radius * 3)
    self.penup()
def middleCircle(self, x=0, y=0, radius = 15, circle_color = "black"):
    '''draw the middle circle'''
    self.pendown()
    self.circle(radius * 2)
    self.penup()
def topCircle(self, x=0, y=0, radius = 15, circle_color = "black"):
    '''draw the top circle'''
    self.pendown()
    self.circle(radius)
    self.penup()
def drawSnowman(self, x=0, y=0, radius = 15, circle_color = "black"):
    self.bottomCircle()
    self.goto(0,radius * 6)
    self.middleCircle()
    self.goto(0,(radius * 6)+(radius * 4))
    self.topCircle()
    self.goto(-(radius) * (0.5),(radius * 6)+(radius * 4)+(radius))
    self.leftEye()
    self.goto((radius) * (0.5),(radius * 6)+(radius * 4)+(radius))
    self.rightEye()
    self.goto(0,(radius * 6)+(radius * 4)+(radius))
    self.drawNose()
    self.bottomOfHat()
    self.topOfHat()



t = MyTurtle()
t.hideturtle()
radius = 15
t.drawSnowman(x = 25,y = 25,radius = 25)

这是我使用参数时的雪人图片 t.drawsnowman(x = 25 y=25 半径 = 25)

这是我不输入参数时的雪人 t.drawsnowman()

Answer 1

尝试逐步了解您的代码实际执行的操作（或使用调试器）。

• 如果你打电话给t.drawSnowman()，radius会15。
• 您调用bottomCircle() 将绘制一个半径为radius * 3 = 45 的圆
• 你在 y 轴上移动 radius * 6 = 90（你现在“在”圆的顶部）
• 你打电话给middleCircle()，这将是一个半径为radius * 2 = 30的圆
• ...

现在，看看如果你用参数调用你的函数会发生什么：

• 如果你打电话给t.drawSnowman(x = 25,y = 25,radius = 25)，radius会25。
• 您调用bottomCircle() 将绘制一个半径为radius * 3 = 45 的圆。注意局部变量radius 是15，因为它是该参数的默认值，并且您不会将传递给drawSnowman 的值传递给bottomCircle 方法。
• 您在 y 轴上移动 radius * 6 = 150（您现在远离圆）
• 您调用middleCircle()，这将是一个半径为radius * 2 = 30 的圆。注意局部变量radius 也是15。
• ...

所以，您的问题是您为radius 传递了一个值，但您只使用该值将海龟移动到drawSnowman，而不是在任何其他函数中进一步向下移动。