Initial data commit

Task/Animate-a-pendulum/Python/animate-a-pendulum-2.py

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+''' Python 3.6.5 code using Tkinter graphical user interface.'''
+
+from tkinter import *
+import math
+
+class Animation:
+    def __init__(self, gw):
+        self.window = gw
+        self.xoff, self.yoff = 300, 100
+        self.angle = 0
+        self.sina = math.sin(self.angle)
+        self.cosa = math.cos(self.angle)
+        self.rodhyp = 170
+        self.bobr = 30
+        self.bobhyp = self.rodhyp + self.bobr
+        self.rodx0, self.rody0 = self.xoff, self.yoff
+        self.ra = self.rodx0
+        self.rb = self.rody0
+        self.rc = self.xoff + self.rodhyp*self.sina
+        self.rd = self.yoff + self.rodhyp*self.cosa
+        self.ba = self.xoff - self.bobr + self.bobhyp*self.sina
+        self.bb = self.yoff - self.bobr + self.bobhyp*self.cosa
+        self.bc = self.xoff + self.bobr + self.bobhyp*self.sina
+        self.bd = self.yoff + self.bobr + self.bobhyp*self.cosa
+        self.da = math.pi / 360
+
+        # create / fill canvas:
+        self.cnv = Canvas(gw, bg='lemon chiffon')
+        self.cnv.pack(fill=BOTH, expand=True)
+
+        self.cnv.create_line(0, 100, 600, 100,
+                             fill='dodger blue',
+                             width=3)
+        radius = 8
+        self.cnv.create_oval(300-radius, 100-radius,
+                             300+radius, 100+radius,
+                             fill='navy')
+
+        self.bob = self.cnv.create_oval(self.ba,
+                                        self.bb,
+                                        self.bc,
+                                        self.bd,
+                                        fill='red',
+                                        width=2)
+
+        self.rod = self.cnv.create_line(self.ra,
+                                        self.rb,
+                                        self.rc,
+                                        self.rd,
+                                        fill='dodger blue',
+                                        width=6)
+
+        self.animate()
+
+    def animate(self):
+        if abs(self.angle) > math.pi / 2:
+            self.da = - self.da
+        self.angle += self.da
+        self.sina = math.sin(self.angle)
+        self.cosa = math.cos(self.angle)
+        self.ra = self.rodx0
+        self.rb = self.rody0
+        self.rc = self.xoff + self.rodhyp*self.sina
+        self.rd = self.yoff + self.rodhyp*self.cosa
+        self.ba = self.xoff - self.bobr + self.bobhyp*self.sina
+        self.bb = self.yoff - self.bobr + self.bobhyp*self.cosa
+        self.bc = self.xoff + self.bobr + self.bobhyp*self.sina
+        self.bd = self.yoff + self.bobr + self.bobhyp*self.cosa
+
+        self.cnv.coords(self.rod,
+                        self.ra,
+                        self.rb,
+                        self.rc,
+                        self.rd)
+        self.cnv.coords(self.bob,
+                        self.ba,
+                        self.bb,
+                        self.bc,
+                        self.bd)
+        self.window.update()
+        self.cnv.after(5, self.animate)
+
+root = Tk()
+root.title('Pendulum')
+root.geometry('600x400+100+50')
+root.resizable(False, False)
+a = Animation(root)
+root.mainloop()