Visualization of Sieve of Eratosthenes algorithm (#181)

* Visualization of Sieve of Eratosthenes algorithm

* Added pygame dependency

* Re-arranged code

Author: hs2361

Code-Sleep-Python/Prime/sieve_of_eratosthenes.py

@@ -0,0 +1,154 @@
+import pygame
+import tkinter
+import math  # importing modules
+pygame.init()
+num = 0
+WHITE = (255, 255, 255)
+BLACK = (0, 0, 0)
+GREEN = (0, 255, 0)
+MAUVE = (224, 176, 255)  # colour tuples to be used later in the program
+clock = pygame.time.Clock()
+
+
+def get_num(m, n):
+    global num
+    num = int(n.get())  # gets value of num from Tkinter GUI
+    m.destroy()  # destroys root window
+
+
+def text_objects(text, font):
+    '''
+    Function to create TextSurface and TextRect objects for
+    displaying text on the PyGame window.
+    It takes 2 parameters:
+        text : the text to be displayed
+        font : pygame.font.Font object in which the text is to be rendered
+    '''
+    textSurface = font.render(text, True, BLACK)
+    return textSurface, textSurface.get_rect()
+
+
+def message_display(text, x, y, size):
+    '''
+    Function to display the given 'text' message
+    at a position of (x,y) in size 'size'
+    '''
+    largeText = pygame.font.Font('freesansbold.ttf', size)
+    TextSurf, TextRect = text_objects(text, largeText)
+    TextRect.center = (x, y)
+    display.blit(TextSurf, TextRect)
+    pygame.display.update()
+
+
+class Cell:  # creating a class for Cell objects on the grid
+    def __init__(self, x, y, n):
+        self.pos = (x, y)
+        self.value = n
+        self.highlighted = False
+        # adding the number and cell pair to the celldict dictionary
+        celldict[self.value] = self
+        # display the value of the cell on the grid at the center of the cell
+        message_display(f"{self.value}", x + 16, y + 16, 17)
+
+    def highlight(self):
+        if not self.highlighted:
+            x, y = self.pos
+            # create a MAUVE rectangle on top of the cell to highlight
+            # composite numbers
+            pygame.draw.rect(display, MAUVE, (x, y, 32, 32))
+            # rewrite the value of the cell on top of the MAUVE highlight
+            message_display(f"{self.value}", x + 16, y + 16, 17)
+            # to avoid time to re-highlight cells that have already been
+            # highlighted
+            self.highlighted = True
+            # for the effect of moving highlight or "scanning" the grid
+            pygame.time.wait(50)
+
+
+# getting user input from GUI
+m = tkinter.Tk()  # root window
+l1 = tkinter.Label(m, text='Enter a number', width=25)  # label widget
+n = tkinter.Entry(m)  # entry widget
+
+# calculate button bounded to get_num function
+btn = tkinter.Button(m, text='Calculate', command=lambda: get_num(m, n))
+l1.pack()
+n.pack()
+btn.pack()  # using pack() geometry manager
+m.mainloop()  # start GUI
+
+# setting up grid
+sq_num = num
+if (math.floor(math.sqrt(num))**2 - num != 0):
+    # getting nearest square greater than or equal to num
+    sq_num = (math.floor(math.sqrt(num)) + 1)**2
+dim = int(sq_num**0.5)  # number of rows and columns of the window
+
+# creating a window having 'dim' rows and columns. Each cell has width of 32px
+width = 32 * dim
+display = pygame.display.set_mode((width, width))
+display.fill(WHITE)  # fill the display with WHITE color
+
+for i in range(0, width, 32):
+    pygame.draw.line(display, BLACK, (i, 0), (i, width)
+                     )  # drawing row lines 32px apart
+for j in range(0, width, 32):
+    # drawing column lines 32px apart
+    pygame.draw.line(display, BLACK, (0, j), (width, j))
+pygame.display.update()
+
+celldict = {}  # dictionary to map numbers to their respective cells
+
+count = 1
+for i in range(0, width, 32):
+    # to deal with internal PyGame events in the event queue which cause the
+    # system to freeze
+    pygame.event.pump()
+    for j in range(0, width, 32):
+        if (count <= num):
+            # create a Cell object at every grid intersection
+            cell = Cell(j, i, count)
+            clock.tick()
+            count += 1
+        else:
+            break
+pygame.display.update()
+# Sieving algorithm
+# all the numbers except 1 since 1 is neither prime nor composite
+nums = set(range(2, num + 1))
+composites = {1}  # set of composites detected so far
+celldict[1].highlight()  # highlight the Cell 1
+
+for i in range(
+        2,
+        round(
+            math.sqrt(num)) +
+        1):  # check all numbers till sqrt(num)
+    if i not in composites:
+        # cross out all the multiples of prime numbers
+        comp = [i * k for k in range(2, num // i + 1)]
+        composites.update(comp)
+        for val in comp:
+            pygame.event.pump()
+            celldict[val].highlight()  # highlight the composites
+
+primetxt = ''  # string of primes to be displayed
+for val, cell in celldict.items():
+    pygame.event.pump()
+    if not cell.highlighted:  # if the cell has not been highlighted
+                              # it is prime
+        x, y = cell.pos
+        # highlight the primes with GREEN
+        pygame.draw.rect(display, GREEN, (x, y, 32, 32))
+        message_display(f"{val}", x + 16, y + 16, 17)
+        pygame.time.wait(100)  # to create a moving highlight
+        primetxt += str(val) + ' ,'  # concatenate primes to primetxt string
+
+# Displaying results using GUI
+m = tkinter.Tk()  # root window
+l1 = tkinter.Label(m, text='Primes that were sieved: ')
+# Message widget to display the sieved primes
+msg = tkinter.Message(m, text=primetxt[:-1], width=200)
+l1.pack()
+msg.pack()
+m.mainloop()

requirements.txt

@@ -6,5 +6,5 @@ scikit-learn >= 0.19
 bokeh >= 0.12
 requests >= 2.18
 msvcrt >= 0.14.0
-
+pygame >= 1.9.6