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.
quit – 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`

# Fly for 1 second.
drone.take_off(climb_to=500)
wait(1, SECONDS)
drone.land()

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 back and forth four times then land.
drone.take_off(climb_to=500)
for i in range(4):
    drone.move_for(direction=0, distance=500, velocity=50, units=MM)
    wait(1, SECONDS)
    drone.move_for(direction=180, distance=500, velocity=50, units=MM)
    wait(1, SECONDS)
drone.land()

# Print each item in a list.
colors = ["Red", "Green", "Blue"]
for color in colors:
    controller.screen.print(color)
    controller.screen.next_row()

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.

# Take a picture when button 5 is pressed.
drone.take_off(climb_to=500)
while True:
    # Move with controller
    drone.move_with_vectors(
        forward=controller.axis4.position(),
        rightward=controller.axis3.position(),
        upward=controller.axis1.position(),
        rotation=controller.axis2.position()
    )

    if controller.button5.pressing():
        drone.camera.capture_image(FORWARD_CAMERA)

    wait(5, MSEC)

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.

# Climb when the left joystick is moved up.
drone.take_off(climb_to=500)
while True:
    if controller.axis1.position() > 0:
        drone.climb(direction=UP, velocity=50)
    else:
        drone.hover()
    wait(5, MSEC)

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.

# Move the drone up or down based on the position of the joystick.
drone.take_off(climb_to=500)
while True:
    position = controller.axis1.position()
    if position > 0:
        drone.climb(direction=UP, velocity=50)
    elif position < 0:
        drone.climb(direction=DOWN, velocity=50)
    else:
        drone.hover()
    wait(5, MSEC)

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.

# Hover at 200 mm.
drone.take_off(climb_to=500)
while drone.range.get_distance(DOWNWARD_RANGE, MM) > 200:
    drone.climb(direction=DOWN, velocity=10)
drone.hover()
wait(3, SECONDS)
drone.land()

break #

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

# Land when button 5 is pressed.
drone.take_off(climb_to=500)
while True:
    # Move with controller
    drone.move_with_vectors(
        forward=controller.axis4.position(),
        rightward=controller.axis3.position(),
        upward=controller.axis1.position(),
        rotation=controller.axis2.position()
    )
    if controller.button5.pressing():
        break
    wait(5, MSEC)
drone.land()

quit #

quit ends a running project.

Usage:
quit()

Parameters	Description
	This method has no parameters.

# Land when button 5 is pressed.
drone.take_off(climb_to=500)
while True:
    # Move with controller
    drone.move_with_vectors(
        forward=controller.axis4.position(),
        rightward=controller.axis3.position(),
        upward=controller.axis1.position(),
        rotation=controller.axis2.position()
    )
    if controller.button5.pressing():
        quit()
    wait(5, MSEC)
drone.land()

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