"""Digital Stream, by Al Sweigart al@inventwithpython.com
A screensaver in the style of The Matrix movie's visuals.
This code is available at https://nostarch.com/big-book-small-python-programming
Tags: tiny, artistic, beginner, scrolling"""
import random, shutil, sys, time
# Set up the constants:
MIN_STREAM_LENGTH = 6 # (!) Try changing this to 1 or 50.
MAX_STREAM_LENGTH = 14 # (!) Try changing this to 100.
PAUSE = 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.
# Get the size of the terminal window:
WIDTH = shutil.get_terminal_size()[0]
# We can't print to the last column on Windows without it adding a
# newline automatically, so reduce the width by one:
WIDTH -= 1
print('Digital Stream, by Al Sweigart al@inventwithpython.com')
print('Press Ctrl-C to quit.')
time.sleep(2)
try:
# 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
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.
sys.stdout.flush() # Make sure text appears on the screen.
time.sleep(PAUSE)
except KeyboardInterrupt:
sys.exit() # When Ctrl-C is pressed, end the program.