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# 10.36 (Tkinter: linear search animation) Write a program that animates the linear
# search algorithm. Create a list that consists of 20 distinct numbers from 1 to
# 20 in a random order. The elements are displayed in a histogram, as shown in
# Figure 10.17. You need to enter a search key in the text field. Clicking the
# Step button causes the program to perform one comparison in the algorithm
# and repaints the histogram with a bar indicating the search position. When
# the algorithm is finished, display a dialog box to inform the user. Clicking the
# Reset button creates a new random list for a new start.
from tkinter import * # Import tkinter
import tkinter.messagebox
import random
class StepControl:
def __init__(self):
self.list = [x for x in range(1, 20)]
self.reset()
self.key = 0
def reset(self):
self.i = -1 # current index
self.done = False
random.shuffle(self.list)
self.drawAStep()
def step(self):
if self.done:
tkinter.messagebox.showinfo("showinfo", "Key is found")
return
if self.i == -1:
self.i += 1
self.drawAStep()
if self.i >= 0 and self.list[self.i] == self.key:
self.done = True
tkinter.messagebox.showinfo("showinfo", "Key is found")
elif self.i >= len(self.list) - 1:
tkinter.messagebox.showinfo("showinfo", "Key is not found")
else:
self.i += 1 # Continue to the next
def drawAStep(self):
bottomGap = 10
canvas.delete("line")
canvas.create_line(10, height - bottomGap, width - 10, height - bottomGap, tag="line")
barWidth = (width - 20) / len(self.list)
maxCount = int(max(self.list))
for i in range(len(self.list)):
canvas.create_rectangle(i * barWidth + 10, (height - bottomGap) * (1 - self.list[i] / (maxCount + 4)),
(i + 1) * barWidth + 10, height - bottomGap, tag="line")
canvas.create_text(i * barWidth + 10 + barWidth / 2,
(height - bottomGap) * (1 - self.list[i] / (maxCount + 4)) - 8,
text=str(self.list[i]), tag="line")
if self.i >= 0:
canvas.create_rectangle(self.i * barWidth + 10,
(height - bottomGap) * (1 - self.list[self.i] / (maxCount + 4)),
(self.i + 1) * barWidth + 10, height - bottomGap, fill="red", tag="line")
def step():
control.key = float(key.get())
control.step()
def reset():
control.reset()
window = Tk() # Create a window
window.title("Linear Search Animation") # Set title
width = 340
height = 150
radius = 2
canvas = Canvas(window, width=width, height=height)
canvas.pack()
frame = Frame(window)
frame.pack()
Label(frame, text="Enter a key (in float):").pack(side=LEFT)
key = StringVar()
Entry(frame, textvariable=key, justify=RIGHT, width=3).pack(side=LEFT)
Button(frame, text="Step", command=step).pack(side=LEFT)
Button(frame, text="Reset", command=reset).pack(side=LEFT)
control = StepControl()
control.drawAStep()
window.mainloop() # Create an event loop
