Pascal's triangle mod everything thing.py

from PIL import Image
import operator as op
from functools import reduce

def nCr(n, r): #Just n choose k
    r = min(r, n-r)
    numer = reduce(op.mul, range(n, n-r, -1), 1)
    denom = reduce(op.mul, range(1, r+1), 1)
    return numer//denom

class PascalTriangle:
    def __init__(self, start_row, end_row, only_odds_and_two, only_left_half, crop_ones):
        self.only_left_half = only_left_half
        self.only_odds_and_two = only_odds_and_two
        count_step = 2 if only_odds_and_two else 1


        starting_element = 1 if crop_ones else 0
        
        self.rows = []
        for row_index in range(start_row, end_row, count_step):
            
            ending_element = row_index//2 if only_left_half else row_index
            self.rows.append([nCr(row_index, element) for element in range(starting_element, ending_element + 1)])
            if row_index % 50 == 0: print('Completed row #', row_index, sep = '')
            
        self.width = len(self.rows[-1])
        self.height = len(self.rows)
        
def generate_primality_visual(triangle, fill_mod):
    #COLORS:
    DOMAIN       = (0x00, 0x00, 0x00)
    OFF_WHITE    = (0xAA, 0xAA, 0xAA)
    
    scale_width = 2 if triangle.only_left_half else  1
    
    img = Image.new("RGB", (triangle.width * scale_width, triangle.height), OFF_WHITE)
    pixels = img.load()

    print("Image size:", img.width, "x", img.height)

    for y in range(triangle.height):
        current_row = triangle.rows[y]
        offset = int((img.width - len(current_row) * scale_width)/2)

        for x in range(len(current_row)):
            mod_value = current_row[x] % y

            try:
                if mod_value == 0:
                    pixels[x + offset, y] = DOMAIN

                elif fill_mod:
                    percent = mod_value/y
                    target_shade = (int(percent*255), int(percent*255), int(percent*255)
                    pixels[x + offset, y] = target_shade

            except Exception as e:
                print("Failed coordinate writing: (%s, %s)." % (x + offset, y))
                raise

        if triangle.only_left_half:
            offset += 2;
            for x in range(len(current_row)):
                mod_value = current_row[x] % y

                try:
                    if mod_value == 0:
                        pixels[img.width - x - offset, y] = DOMAIN
                    elif fill_mod:
                        percent = mod_value/y
                        target_shade = (int(percent*255), int(percent*255), int(percent*255)
                        pixels[img.width - x - offset, y] = target_shade;
                except Exception as e:
                    print("Failed coordinate writing (right half): (%s, %s)." % (x + offset, y))
                    raise

    return img

if __name__ == '__main__':
    start, end = 0, 2048 #Feel free to change this

    print("Making triangle rows %s - %s." % (start, end))
    triangle = PascalTriangle(start, end, False, True, True)
    print("Done making triangle.")

    #Recommendation: Pickle triangle so it can be loaded faster later
    #with open('./triangle.pickle', 'wb') as f: pickle.dump(triangle, f)
    #Then load it with:    
    #with open('./triangle.pickle', 'rb') as f: triangle = pickle.load(f)
    
    image = generate_primality_visual(triangle, True)
    image.save("./triangle.png")

What is generated: