Plot Transform Functions#

In the Roboto Visualizer, the Y Transform field in the plot series settings lets you apply a mathematical formula to transform the Y values of a series. This is useful for unit conversion, normalization, scaling, and other on-the-fly calculations.

The formula is written as an expression in terms of the variable y, which represents the raw signal value at each point in time.

Examples#

Formula	Effect
`y * 57.2958`	Convert radians to degrees
`y / 9.81`	Convert m/s² to g-force
`y * 3.28084`	Convert metres to feet
`m * y + b`	Linear scale and offset (replace `m` and `b` with numbers)
`abs(y)`	Absolute value
`sqrt(y)`	Square root
`round(y * 100) / 100`	Round to two decimal places
`log(y)`	Natural logarithm

Supported Operators#

Operator	Description
`+`	Addition
`-`	Subtraction
`*`	Multiplication
`/`	Division
`%`	Modulo (remainder)
`^`	Exponentiation (e.g. `y^2` squares the value)

Supported Functions#

Function	Description
`abs(y)`	Absolute value
`sqrt(y)`	Square root
`pow(y, n)`	Raise `y` to the power `n`
`sin(y)`	Sine (argument in radians)
`cos(y)`	Cosine (argument in radians)
`tan(y)`	Tangent (argument in radians)
`log(y)`	Natural logarithm (base e)
`exp(y)`	Exponential (e raised to the power `y`)
`min(a, b)`	Smaller of two values
`max(a, b)`	Larger of two values
`round(y)`	Round to the nearest integer
`floor(y)`	Round down to the nearest integer
`ceil(y)`	Round up to the nearest integer

Supported Constants#

Constant	Value
`PI`	π ≈ 3.14159265358979
`E`	e ≈ 2.71828182845905

Usage Notes#

The variable y is the only supported input variable. It represents the raw signal value at a given timestamp.
Functions and constants are case-sensitive: use sqrt not Sqrt, and PI not pi.

Beyond Dynamic Transforms#

The Y Transform field is designed for simple, single-variable expressions. If your use case requires something more complex — such as combining multiple signals, applying stateful filters, resampling, or computing rolling statistics — consider creating a derived topic as part of your ingestion pipeline using a Roboto Action.

An Action runs on hosted compute after a file is ingested and can write new topics back to Roboto using the Python SDK. Those derived topics then appear alongside the original signals in the visualizer and can be plotted directly, without any runtime transform.

See Process data with actions and Create your own action for a full walkthrough, and the Python SDK reference for the topic-writing APIs.