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_project – Ends the running project.
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`

def main():
    # Turn right for one second, then stop
    drivetrain.turn(RIGHT)
    wait(1, SECONDS)
    drivetrain.stop()

# VR threads — Do not delete
vr_thread(main)

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).

def main():
    # Move in a square path
    for index in range(4):
        drivetrain.drive_for(FORWARD, 100, MM)
        drivetrain.turn_for(RIGHT, 90, DEGREES)

# VR threads — Do not delete
vr_thread(main)

def main():
    # Print each item in the list
    colors = ["Red", "Green", "Blue"]

    for color in colors:
        brain.print(color)
        brain.new_line()

# VR threads — Do not delete
vr_thread(main)

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.

def main():
    # Turn right until facing south
    while True:
        if drivetrain.heading(DEGREES) < 180:
            drivetrain.turn_for(RIGHT, 90, DEGREES)
        wait(0.1, SECONDS)

# VR threads — Do not delete
vr_thread(main)

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.

def main():
    # Drive after turning around
    while True:
        if drivetrain.rotation(DEGREES) < 180:
            drivetrain.turn_for(RIGHT, 90, DEGREES)
        else:
            drivetrain.drive(FORWARD)
        wait(0.1, SECONDS)

# VR threads — Do not delete
vr_thread(main)

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.

def main():
    # Move depending on the detected color
    while True:
        if front_eye.detect(RED):
            drivetrain.drive(FORWARD)
        elif front_eye.detect(GREEN):
            drivetrain.drive(REVERSE)
        else:
            drivetrain.turn(RIGHT)
        wait(0.1, SECONDS)

# VR threads — Do not delete
vr_thread(main)

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.

def main():
    while True:
        # Move in a square path forever
        drivetrain.drive_for(FORWARD, 150, MM)
        drivetrain.turn_for(RIGHT, 90, DEGREES)

# VR threads — Do not delete
vr_thread(main)

def main():
    # Wait until an object is detected to stop driving
    drivetrain.drive(FORWARD)
    while not front_distance.found_object():
        wait(50, MSEC)
    drivetrain.stop()

# VR threads — Do not delete
vr_thread(main)

break #

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

def main():
    # Stop turning after a button is pressed
    while True:
        drivetrain.turn(RIGHT)
        if front_distance.found_object():
            break
    drivetrain.stop()

# VR threads — Do not delete
vr_thread(main)

stop_project #

stop_project ends a running project.

Usage:
stop_project()

Parameters	Description
	This method has no parameters.

def main():
    # Stop the project after a button is pressed
    while True:
        drivetrain.turn(RIGHT)
        if front_distance.found_object():
            stop_program()
        drivetrain.drive(FORWARD)

# VR threads — Do not delete
vr_thread(main)

pass #

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

if condition:
    pass

def function():
    pass