無法判斷Python函數是否正在調用？

Question

我無法獲得此代碼的工作。它應該從輸入函數生成一個分形圖像。它將完美運行，然後打印出單色帆布而不是分形。當我將Mandelbrot的分形函數切換到Newton-Raphson時，出現了這個問題。與Mandelbrot不同，Newton-Raphson需要一個單獨的定義來調用函數。這是給我麻煩的一點。我輸入了一個打印語句，它似乎正在運行，但它運行不正常。它運行所有的點到最大迭代（MaxIt），然後給我一個單一的彩色畫布，認爲他們都逃到無限。以下是當前代碼的副本：

from tkinter import * 
from math import * 

#Creates widgets for user input 
class Imagespecs(Frame): 

    def __init__(self,master): 
     Frame.__init__(self,master) 
     self.grid() 
     self.y_axis() 
     self.x_axis() 

#Y axis input 
    def y_axis(self): 
     self.instruction = Label(self,text = "How many pixels high do you want the image?") 
     self.instruction.grid(row = 8, column = 0, columnspan = 2, sticky = N) 

     self.height = Entry(self) 
     self.height.grid(row = 10, column = 1, sticky = E) 

#Enters info to run fractal generation 
     self.submit_button = Button(self,text = "Submit", command = self.fractals) 
     self.submit_button.grid(row = 14, column = 2, sticky = E) 

#X axis input 
    def x_axis(self): 
     self.instruction2 = Label(self,text = "How many pixels wide do you want the image?") 
     self.instruction2.grid(row = 4, column = 0, columnspan = 2, sticky = E) 

     self.width = Entry(self) 
     self.width.grid(row = 6, column = 1, sticky = E) 

#generates fractal 
    def fractals(self): 
     maxIt = 2 
     ds = 0.2e-1 
     eps = 5e-5 
     #Replace non-input 
     content = self.width.get() 
     content2 = self.height.get() 

     if content == "": 
      content = 500 

     if content2 == "": 
      content2 = 500 

     def f(z): 
      return z**3 + 5 
     print ('lalala') 

     #Create window specs 
     WIDTH = int(content2); HEIGHT = int(content) 
     xa = -1.0; xb = 1.0 
     ya = -1.0; yb = 1.0 
     maxIt = 300 

     window = Toplevel() 
     canvas = Canvas(window, width = WIDTH, height = HEIGHT, bg = "#000000") 
     img = PhotoImage(width = WIDTH, height = HEIGHT) 
     canvas.create_image((0, 0), image = img, state = "normal", anchor = NW) 

     #The Newton-Raphson iteration 
     h = HEIGHT 
     for y in range(HEIGHT): 
      print (h) 
      h = h - 1 
      zy = y * (yb - ya)/(HEIGHT - 1) + ya 
      for x in range(WIDTH): 
       zx = x * (xb - xa)/(WIDTH - 1) + xa 
       z = complex(zx, zy) 
       for i in range(maxIt): 
        dz = (f(z + complex(ds, ds)) - f(z))/complex(ds, ds) 
        z0 = z - f(z)/dz 
        if abs(z0 - z) < eps: 
         break 

       rd = hex(i % 4 * 64)[2:].zfill(2) 
       gr = hex(i % 8 * 32)[2:].zfill(2) 
       bl = hex(i % 16 * 16)[2:].zfill(2) 
       img.put("#" + rd + gr + bl, (x, y)) 


     #Run GUI 
     canvas.pack() 
     mainloop() 

#Run the class and everything else  
root = Tk() 
root.title("Fractal GUI") 
root.geometry("300x200") 
app = Imagespecs(root) 

root.mainloop() 

Answer 1

儘管代碼中存在錯誤，例如缺少z = z0線，這裏的主要罪魁禍首是的Tkinter的光象的已知功能具有不保存到圖片和垃圾收集引用做：

Why do my Tkinter images not appear?

我返工你的代碼來生成一個分形和嘗試要解決這些問題，我注意到：

from tkinter import * 

MAX_ITERATIONS = 300 
DS = 0.2e-1 
EPS = 5e-5 

# Create window specs 
XA, XB = -1.0, 1.0 
YA, YB = -1.0, 1.0 

# Creates widgets for user input 
class Imagespecs(Frame): 

    def __init__(self, master): 
     Frame.__init__(self, master) 
     self.grid() 
     self.y_axis() 
     self.x_axis() 
     self.image = None 

    # Y axis input 
    def y_axis(self): 
     instruction = Label(self, text="How many pixels high do you want the image?") 
     instruction.grid(row=8, column=0, columnspan=2, sticky=N) 

     self.height = Entry(self) 
     self.height.grid(row=10, column=1, sticky=E) 

     # Enters info to run fractal generation 
     submit_button = Button(self, text="Submit", command=self.fractals) 
     submit_button.grid(row=14, column=2, sticky=E) 

    # X axis input 
    def x_axis(self): 
     instruction = Label(self, text="How many pixels wide do you want the image?") 
     instruction.grid(row=4, column=0, columnspan=2, sticky=E) 

     self.width = Entry(self) 
     self.width.grid(row=6, column=1, sticky=E) 

    # generates fractal 
    def fractals(self): 

     def f(z): 
      return z**3 + 5 

     # Replace non-input 
     try: 
      width = int(self.width.get()) 
     except ValueError: 
      width = 500 

     try: 
      height = int(self.height.get()) 
     except ValueError: 
      height = 500 

     canvas = Canvas(Toplevel(), width=width, height=height, bg="#000000") 
     img = PhotoImage(width=width, height=height) 
     canvas.create_image((0, 0), image=img, state="normal", anchor=NW) 

     # The Newton-Raphson iteration 
     for y in range(height): 
      zy = y * (YB - YA)/(height - 1) + YA 

      for x in range(width): 
       zx = x * (XB - XA)/(width - 1) + XA 
       z = complex(zx, zy) 

       i = 0 # avoid undefined variable after loop 

       for i in range(MAX_ITERATIONS): 
        dz = (f(z + complex(DS, DS)) - f(z))/complex(DS, DS) 
        z0 = z - f(z)/dz 
        if abs(z0 - z) < EPS: 
         break 
        z = z0 

       red = i % 4 * 64 
       green = i % 8 * 32 
       blue = i % 16 * 16 
       img.put("#%02x%02x%02x" % (red, green, blue), (x, y)) 

     # Run GUI 
     canvas.pack() 
     self.image = img # save reference so image isn't GC'd! 

# Run the class and everything else 
root = Tk() 
root.title("Fractal GUI") 
root.geometry("400x150") 

app = Imagespecs(root) 

root.mainloop()