import random, time, os

os.system('cls | clear')  # Clear the screen

# Set up the constants:
MIN_STREAM_LENGTH = 6  # (!) Try changing this to 1 or 50.
MAX_STREAM_LENGTH = 14  # (!) Try changing this to 100.
DELAY = 0.1  # (!) Try changing this to 0.0 or 2.0.
STREAM_CHARS = ['0', '1']  # (!) Try changing this to other characters.

# Density can range from 0.0 to 1.0:
DENSITY = 0.02  # (!) Try changing this to 0.10 or 0.30.


WIDTH = 79  #os.get_terminal_size()[0] - 1

# For each column, when the counter is 0, no stream is shown.
# Otherwise, it acts as a counter for how many times a 1 or 0
# should be displayed in that column.
columns = [0] * WIDTH
try:
    while True:
        # Set up the counter for each column:
        for i in range(WIDTH):
            if columns[i] == 0:
                if random.random() <= DENSITY:
                    # Restart a stream on this column.
                    columns[i] = random.randint(MIN_STREAM_LENGTH,
                                                MAX_STREAM_LENGTH)

            # Display an empty space or a 1/0 character.
            if columns[i] > 0:
                print(random.choice(STREAM_CHARS), end='')
                columns[i] -= 1
            else:
                print(' ', end='')
        print()  # Print a newline at the end of the row of columns.
        time.sleep(DELAY)
except KeyboardInterrupt:
    print('Matrix Screensaver, by Al Sweigart al@inventwithpython.com 2021')