Sorting Algorithm Visualization : Merge Sort
The human brain can easily process visuals instead of long codes to understand the algorithms. In this article, a program that program visualizes the Merge sort Algorithm has been implemented.
The GUI(Graphical User Interface) is implemented using pygame package in python.
Approach:
Examples:
Input :
Press “Enter” key to Perform Visualization.
Press “r” key to generate new array.
Output :
Initial:Visualizing:
Final:
Below is the program to visualize the Merge Sort algorithm:
# Python implementation for visualizing merge sort. import pygameimport randompygame.font.init()# Total windowscreen = pygame.display.set_mode((900, 650)) # Title and Icon pygame.display.set_caption("SORTING VISUALISER")# Place any custom png file in same folder as the source code# and mention it below and uncomment below two lines.# img = pygame.image.load# ('E:/Projects / Sorting Visualiser / sorticon.png')# pygame.display.set_icon(img) # Boolean variable to run the program in while looprun = True # Window sizewidth = 900length = 600array =[0]*151arr_clr =[(0, 204, 102)]*151clr_ind = 0clr =[(0, 204, 102), (255, 0, 0), (0, 0, 153), (255, 102, 0)]fnt = pygame.font.SysFont("comicsans", 30)fnt1 = pygame.font.SysFont("comicsans", 20)# Generate new Arraydef generate_arr(): for i in range(1, 151): arr_clr[i]= clr[0] array[i]= random.randrange(1, 100)generate_arr() def refill(): screen.fill((255, 255, 255)) draw() pygame.display.update() pygame.time.delay(20) # Sorting Algo:Merge sortdef mergesort(array, l, r): mid =(l + r)//2 if l<r: mergesort(array, l, mid) mergesort(array, mid + 1, r) merge(array, l, mid, mid + 1, r)def merge(array, x1, y1, x2, y2): i = x1 j = x2 temp =[] pygame.event.pump() while i<= y1 and j<= y2: arr_clr[i]= clr[1] arr_clr[j]= clr[1] refill() arr_clr[i]= clr[0] arr_clr[j]= clr[0] if array[i]<array[j]: temp.append(array[i]) i+= 1 else: temp.append(array[j]) j+= 1 while i<= y1: arr_clr[i]= clr[1] refill() arr_clr[i]= clr[0] temp.append(array[i]) i+= 1 while j<= y2: arr_clr[j]= clr[1] refill() arr_clr[j]= clr[0] temp.append(array[j]) j+= 1 j = 0 for i in range(x1, y2 + 1): pygame.event.pump() array[i]= temp[j] j+= 1 arr_clr[i]= clr[2] refill() if y2-x1 == len(array)-2: arr_clr[i]= clr[3] else: arr_clr[i]= clr[0] # Draw the array valuesdef draw(): # Text should be rendered txt = fnt.render("PRESS"\ " 'ENTER' TO PERFORM SORTING.", 1, (0, 0, 0)) # Position where text is placed screen.blit(txt, (20, 20)) txt1 = fnt.render("PRESS 'R' FOR NEW ARRAY.", 1, (0, 0, 0)) screen.blit(txt1, (20, 40)) txt2 = fnt1.render("ALGORITHM USED: "\ "MERGE SORT", 1, (0, 0, 0)) screen.blit(txt2, (600, 60)) element_width =(width-150)//150 boundry_arr = 900 / 150 boundry_grp = 550 / 100 pygame.draw.line(screen, (0, 0, 0), (0, 95), (900, 95), 6) for i in range(1, 100): pygame.draw.line(screen, (224, 224, 224), (0, boundry_grp * i + 100), (900, boundry_grp * i + 100), 1) # Drawing the array values as lines for i in range(1, 151): pygame.draw.line(screen, arr_clr[i],\ (boundry_arr * i-3, 100),\ (boundry_arr * i-3, array[i]*boundry_grp + 100),\ element_width) # Infinite loop to keep the window openwhile run: # background screen.fill((255, 255, 255)) # Event handler stores all event for event in pygame.event.get(): # If we click Close button in window if event.type == pygame.QUIT: run = False if event.type == pygame.KEYDOWN: if event.key == pygame.K_r: generate_arr() if event.key == pygame.K_RETURN: mergesort(array, 1, len(array)-1) draw() pygame.display.update() pygame.quit() |
Output:
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