Python#

The VEX IQ (2nd gen) Python API Reference explains what each command, method, and function does, what inputs it uses, what it returns, and how it can be used in a project.

Use this reference when you want to understand a command before adding it to a project, check what values it accepts or returns, or compare related commands in a category.

Python commands are used in VEXcode IQ (2nd gen) Python projects. Blocks and C++ projects use the other API sections instead.

Note: The IQ (2nd gen) Brain runs Python through a virtual machine with limited memory. While there is a maximum source code size, whether a program will run also depends on its complexity (such as the number of functions, variables, and logic used). As a result, programs that are large or complex may fail to compile or run even if they are under the size limit. C/C++ programs are generally less affected by these limits on IQ (2nd gen).

How to Read a Method Entry#

Most Python entries include the following parts:

Command name - The official name of the command, method, or function.
Description - Explains what the command does and when it is useful.
Usage - Shows the syntax used to write the command in code.
Parameters - Lists the inputs the command accepts and explains what each one does.
Return value - Explains what the command reports back, if it returns a value.
Example code - Shows one way the command can be used in a project.

Common Python API Elements#

Element	What it means
Method	A command called on an object such as `drivetrain.drive(…)`.
Function	A command called directly, such as `wait(…)` or `print(…)`.
Parameter	A value passed into a method or function to control what it does.
Optional parameter	A parameter that can be left out so the default behavior is used.
Return value	A value a command reports back, such as a number, text, or Boolean.

Basic Python Vocabulary#

Term	What it means
Variable	A name that stores a value, such as `speed = 50`.
String	Text inside quotes, such as `“Hello”`.
Integer	A positive or negative number, such as `90`.
Float	A number with a decimal, such as `25.5`.
Boolean	A value that is either `True` or `False`.
Argument	A value passed into a method or function call, such as `REVERSE` in `drivetrain.drive(REVERSE, 20, PERCENT)`.

Example Method Entry#

drive#

drive moves the robot forward or reverse forever. The robot will continue to move until it is given another action, like turning or stopping.

Usage:
drivetrain.drive(direction, velocity, units)

Parameters	Description
`direction`	The direction the robot moves: `FORWARD` or `REVERSE`.
`velocity`	Optional. The velocity to drive with from 0% to 100% when using `PERCENT`, from 0 to 120 rpm when using `RPM`, or from 0 to 720 degrees per second when using `VelocityUnits.DPS`. This can be an `integer` or decimal (`float`). If no velocity is provided, the robot drives at the current drive velocity.
`units`	Optional. The velocity unit: `PERCENT` (default), `RPM` (rotations per minute), or `VelocityUnits.DPS` (degrees per second).

# Drive forward then stop
drivetrain.drive(FORWARD)
wait(2, SECONDS)
drivetrain.stop()

# Drive slowly in reverse then stop
drivetrain.drive(REVERSE, 20, PERCENT)
wait(2, SECONDS)
drivetrain.stop()