Documentation

derivative() function

derivative() computes the rate of change per unit of time between subsequent non-null records.

The function assumes rows are ordered by the _time.

Output tables

The output table schema will be the same as the input table. For each input table with n rows, derivative() outputs a table with n - 1 rows.

Function type signature
(
    <-tables: stream[A],
    ?columns: [string],
    ?initialZero: bool,
    ?nonNegative: bool,
    ?timeColumn: string,
    ?unit: duration,
) => stream[B] where A: Record, B: Record
  • Copy
  • Fill window

For more information, see Function type signatures.

Parameters

unit

Time duration used to calculate the derivative. Default is 1s.

nonNegative

Disallow negative derivative values. Default is false.

When true, if a value is less than the previous value, the function assumes the previous value should have been a zero.

columns

List of columns to operate on. Default is ["_value"].

timeColumn

Column containing time values to use in the calculation. Default is _time.

initialZero

Use zero (0) as the initial value in the derivative calculation when the subsequent value is less than the previous value and nonNegative is true. Default is false.

tables

Input data. Default is piped-forward data (<-).

Examples

Calculate the non-negative rate of change per second

import "sampledata"

sampledata.int()
    |> derivative(nonNegative: true)
  • Copy
  • Fill window

View example input and output

Calculate the rate of change per second with null values

import "sampledata"

sampledata.int(includeNull: true)
    |> derivative()
  • Copy
  • Fill window

View example input and output


Was this page helpful?

Thank you for your feedback!


The future of Flux

Flux is going into maintenance mode. You can continue using it as you currently are without any changes to your code.

Read more

Now Generally Available

InfluxDB 3 Core and Enterprise

Start fast. Scale faster.

Get the Updates

InfluxDB 3 Core is an open source, high-speed, recent-data engine that collects and processes data in real-time and persists it to local disk or object storage. InfluxDB 3 Enterprise builds on Core’s foundation, adding high availability, read replicas, enhanced security, and data compaction for faster queries and optimized storage. A free tier of InfluxDB 3 Enterprise is available for non-commercial at-home or hobbyist use.

For more information, check out: