Control#

Introduction #

Control in Python lets you tell the robot when to wait, when to repeat actions, how to make decisions, and when to end the project.

Below is a list of available controls, including methods and core Python keywords:

wait – Pauses the project for a given time.
for – Repeats code for each item in a sequence.
if – Runs code if a condition is true.
if/else – Runs different code depending on a condition.
if/elif/else – Checks multiple conditions in order.
while – Repeats code while a condition is true.
break – Exits a loop immediately.
stop_program – Ends the running program.
pass – Placeholder used when no action is needed.

wait #

wait pauses for a specific amount of time before moving to the next line of code.

Usage:
wait(time, units)

Parameters	Description
`time`	The amount of time to wait, as a positive whole number or decimal.
`units`	The unit that represents the wait time: `MSEC` (default) – milliseconds, or `SECONDS`

# Turn right for one second
robot.turn(RIGHT)
wait(1, SECONDS)
robot.stop()

for #

for repeats a set of actions a specific number of times. for can be used to loop through items in lists, tuples, dictionaries, sets, strings, or for a specified amount of loops with range.

Usage:

for value in expression_list:
    pass

Components	Description
`value`	A temporary variable that stores the current element in the iteration.
`expression_list`	The collection of elements being looped through (e.g., list, string, range).

# Move in a square path
for index in range(4):
    robot.drive_for(FORWARD, 1, STEPS)
    robot.turn_for(RIGHT, 90)

if #

if runs the indented block of code if the condition is True.

Usage:

if condition:
    pass

Components	Description
`condition`	An expression or variable that is checked when the statement runs. If it is `True`, the code inside the `if` block executes; if it is `False`, the block is skipped.

# Turn when the Move button is pressed
while True:
    if robot.get_button(MOVE):
        robot.turn_for(RIGHT, 90)
    wait(0.1, SECONDS)

if/else #

if and else determine which indented block of code runs based on whether the condition is True or False.

Usage:

if condition:
    pass
else:
    pass

Components	Description
`condition`	An expression or variable that is checked when the statement runs. If it is `True`, the code inside the `if` block executes; if it is `False`, the code inside the `else` block executes instead.

# Drive while no button is pressed, stop when one is
while True:
    if robot.get_button(MOVE):
        robot.stop()
    else:
        robot.drive(FORWARD)
    wait(0.1, SECONDS)

if/elif/else #

The if/elif/else structure selects which indented block of code runs based on conditions:

if runs its block if the condition is True.
elif checks additional conditions only if all previous conditions are False. Multiple elif statements can be used.
else runs its block only if none of the previous conditions are True.

Usage:

if condition:
    pass
elif condition:
    pass
else:
    pass

Components	Description
`condition`	An expression or variable that is checked when the statement runs. The first condition that is `True` determines which block executes; if none are `True`, the `else` block runs.

# Change the LED color based on heading while turning
robot.turn(RIGHT)
while True:
    if robot.get_heading() < 120:
        robot.led.glow(OFF)
    elif robot.get_heading() < 240:
        robot.led.glow(BLUE)
    else:
        robot.led.glow(GREEN)
    wait(0.2, SECONDS)

while repeatedly runs code as long as the condition is True. It can also be used like a “forever” by using True as the condition, or a “wait until” by adding not to the condition, as shown in the examples below.

Usage:

while condition:
    pass

Components	Description
`condition`	An expression or variable that is checked before each iteration. If it is `True`, the loop continues; if it is `False`, the loop stops.

# Drive while no button is pressed, stop when one is
while True:
    if robot.get_button(MOVE):
        robot.stop()
    else:
        robot.drive(FORWARD)
    wait(0.1, SECONDS)

# Wait until the Move button is pressed before driving
while not robot.get_button(MOVE):
    wait(0.2, SECONDS)
robot.drive_for(FORWARD, 1, STEPS)

break #

break exits a loop immediately. break can be used to leave loops that otherwise would loop forever.

Usage:

break

Parameters	Description
	This keyword has no parameters.

# Stop driving after pressing the Move button
while True:
    robot.drive(FORWARD)
    if robot.get_button(MOVE):
        break
    wait(0.2, SECONDS)
robot.stop()

stop_program #

stop_program ends a running project.

Usage:
stop_program()

Parameters	Description
	This method has no parameters.

# Stop the project after pressing the Move button
while True:
    robot.drive(FORWARD)
    if robot.get_button(MOVE):
        break
    wait(0.2, SECONDS)
stop_program()

pass #

pass is a placeholder for future code and can be used to avoid errors in empty loops, conditionals, and functions.

Usage:

pass

Parameters	Description
	This keyword has no parameters.

if condition:
    pass

def function():
    pass