1. Intro to Robots Lab 3

2. Intro to Robots Basic Robot Brain Programs consist of import lines, function definitions and and a starting point. Line 1: from myro import * Line 2: initialize("comX") Line 3: Line 4: Line 5: def main(): Line 6: Line 7: Line 8:... Line 9: main() Always start from a function called main()

3. Intro to Robots Exercise Combine the following functions into a program that yoyos and wiggles for a bit. Try to make your dance short and sweet. def yoyo(speed, waitTime): forward(speed, waitTime) backward(speed, waitTime) stop() def wiggle(speed, waitTime): motors(-speed, speed) wait(waitTime) motors(speed, -speed) wait(waitTime) stop()

4. Intro to Robots Exercise: Take the previous program and rename the main() function dance(). Now create a main() function that calls dance(). The problem is if you want to “dance all night”. Call the program dance.py. It works but not very interesting: def main(): dance()...

5. Intro to Robots Repetition in Python (and other languages): Programming languages have syntax for repeating the same thing over and over and over and over... for-loop: when you know exactly how many times to repeat something while-loop: when you don’t know, in advance, exactly how many times you need to repeat something def main(): for i in range(1): dance() def main(): while timeRemaining(10): dance() keeps calling dance() until 10 seconds have passed

6. Intro to Robots Exercise: Modify the dance.py program to use a for-loop.

7. Intro to Robots While-Loops: c(i) is a boolean condition that is True of False depending on the value of i. f() gives a new value to i, once for each iteration through the loop. This loop will go on forever if f() never returns a value for which c(i) == False. i = 0 while c(i): # do something i = f() answer = ‘No’ while answer == ‘No’: dance() answer = ask(‘Again?’) what happens if you never enter ‘No’ but rather ‘no’, ‘n’, NO’, etc.

8. Intro to Robots Infinite Loops: The example on the last slide shows that a loop can, by accident, go on forever. You can also intentionally write an infinite loop. How do you stop this loop? while True: # do something Ctrl-C

9. Intro to Robots Exercise: Modify the dance.py program to replace the for-loop with a while-loop. Try various while-loops including an infinite loop.