---
title: difference() function
description: difference() returns the difference between subsequent values.
url: https://docs.influxdata.com/flux/v0/stdlib/universe/difference/
estimated_tokens: 4201
product: Flux
version: v0
---

# difference() function

-   Flux 0.7.1+
-   View InfluxDB support

`difference()` returns the difference between subsequent values.

### Subtraction rules for numeric types

-   The difference between two non-null values is their algebraic difference; or `null`, if the result is negative and `nonNegative: true`;
-   `null` minus some value is always `null`;
-   Some value `v` minus `null` is `v` minus the last non-null value seen before `v`; or `null` if `v` is the first non-null value seen.
-   If `nonNegative` and `initialZero` are set to `true`, `difference()` returns the difference between `0` and the subsequent value. If the subsequent value is less than zero, `difference()` returns `null`.

### Output tables

For each input table with `n` rows, `difference()` outputs a table with `n - 1` rows.

##### Function type signature

```js
(
    <-tables: stream[A],
    ?columns: [string],
    ?initialZero: bool,
    ?keepFirst: bool,
    ?nonNegative: bool,
) => stream[B] where A: Record, B: Record
```

For more information, see [Function type signatures](/flux/v0/function-type-signatures/).

## Parameters

### nonNegative

Disallow negative differences. 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"]`.

### keepFirst

Keep the first row in each input table. Default is `false`.

If `true`, the difference of the first row of each output table is null.

### initialZero

Use zero (0) as the initial value in the difference 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 difference between subsequent values](#calculate-the-difference-between-subsequent-values)
-   [Calculate the non-negative difference between subsequent values](#calculate-the-non-negative-difference-between-subsequent-values)
-   [Calculate the difference between subsequent values with null values](#calculate-the-difference-between-subsequent-values-with-null-values)
-   [Keep the first value when calculating the difference between values](#keep-the-first-value-when-calculating-the-difference-between-values)

### Calculate the difference between subsequent values

```js
import "sampledata"

sampledata.int()
    |> difference()
```

[](#view-example-input-and-output)

View example input and output

#### Input data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | -2 | t1 |
| 2021-01-01T00:00:10Z | 10 | t1 |
| 2021-01-01T00:00:20Z | 7 | t1 |
| 2021-01-01T00:00:30Z | 17 | t1 |
| 2021-01-01T00:00:40Z | 15 | t1 |
| 2021-01-01T00:00:50Z | 4 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | 19 | t2 |
| 2021-01-01T00:00:10Z | 4 | t2 |
| 2021-01-01T00:00:20Z | -3 | t2 |
| 2021-01-01T00:00:30Z | 19 | t2 |
| 2021-01-01T00:00:40Z | 13 | t2 |
| 2021-01-01T00:00:50Z | 1 | t2 |

#### Output data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:10Z | 12 | t1 |
| 2021-01-01T00:00:20Z | -3 | t1 |
| 2021-01-01T00:00:30Z | 10 | t1 |
| 2021-01-01T00:00:40Z | -2 | t1 |
| 2021-01-01T00:00:50Z | -11 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:10Z | -15 | t2 |
| 2021-01-01T00:00:20Z | -7 | t2 |
| 2021-01-01T00:00:30Z | 22 | t2 |
| 2021-01-01T00:00:40Z | -6 | t2 |
| 2021-01-01T00:00:50Z | -12 | t2 |

### Calculate the non-negative difference between subsequent values

```js
import "sampledata"

sampledata.int()
    |> difference(nonNegative: true)
```

[](#view-example-input-and-output)

View example input and output

#### Input data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | -2 | t1 |
| 2021-01-01T00:00:10Z | 10 | t1 |
| 2021-01-01T00:00:20Z | 7 | t1 |
| 2021-01-01T00:00:30Z | 17 | t1 |
| 2021-01-01T00:00:40Z | 15 | t1 |
| 2021-01-01T00:00:50Z | 4 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | 19 | t2 |
| 2021-01-01T00:00:10Z | 4 | t2 |
| 2021-01-01T00:00:20Z | -3 | t2 |
| 2021-01-01T00:00:30Z | 19 | t2 |
| 2021-01-01T00:00:40Z | 13 | t2 |
| 2021-01-01T00:00:50Z | 1 | t2 |

#### Output data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:10Z | 12 | t1 |
| 2021-01-01T00:00:20Z |  | t1 |
| 2021-01-01T00:00:30Z | 10 | t1 |
| 2021-01-01T00:00:40Z |  | t1 |
| 2021-01-01T00:00:50Z |  | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:10Z |  | t2 |
| 2021-01-01T00:00:20Z |  | t2 |
| 2021-01-01T00:00:30Z | 22 | t2 |
| 2021-01-01T00:00:40Z |  | t2 |
| 2021-01-01T00:00:50Z |  | t2 |

### Calculate the difference between subsequent values with null values

```js
import "sampledata"

sampledata.int(includeNull: true)
    |> difference()
```

[](#view-example-input-and-output)

View example input and output

#### Input data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | -2 | t1 |
| 2021-01-01T00:00:10Z |  | t1 |
| 2021-01-01T00:00:20Z | 7 | t1 |
| 2021-01-01T00:00:30Z |  | t1 |
| 2021-01-01T00:00:40Z |  | t1 |
| 2021-01-01T00:00:50Z | 4 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z |  | t2 |
| 2021-01-01T00:00:10Z | 4 | t2 |
| 2021-01-01T00:00:20Z | -3 | t2 |
| 2021-01-01T00:00:30Z | 19 | t2 |
| 2021-01-01T00:00:40Z |  | t2 |
| 2021-01-01T00:00:50Z | 1 | t2 |

#### Output data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:10Z |  | t1 |
| 2021-01-01T00:00:20Z | 9 | t1 |
| 2021-01-01T00:00:30Z |  | t1 |
| 2021-01-01T00:00:40Z |  | t1 |
| 2021-01-01T00:00:50Z | -3 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:10Z |  | t2 |
| 2021-01-01T00:00:20Z | -7 | t2 |
| 2021-01-01T00:00:30Z | 22 | t2 |
| 2021-01-01T00:00:40Z |  | t2 |
| 2021-01-01T00:00:50Z | -18 | t2 |

### Keep the first value when calculating the difference between values

```js
import "sampledata"

sampledata.int()
    |> difference(keepFirst: true)
```

[](#view-example-input-and-output)

View example input and output

#### Input data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | -2 | t1 |
| 2021-01-01T00:00:10Z | 10 | t1 |
| 2021-01-01T00:00:20Z | 7 | t1 |
| 2021-01-01T00:00:30Z | 17 | t1 |
| 2021-01-01T00:00:40Z | 15 | t1 |
| 2021-01-01T00:00:50Z | 4 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | 19 | t2 |
| 2021-01-01T00:00:10Z | 4 | t2 |
| 2021-01-01T00:00:20Z | -3 | t2 |
| 2021-01-01T00:00:30Z | 19 | t2 |
| 2021-01-01T00:00:40Z | 13 | t2 |
| 2021-01-01T00:00:50Z | 1 | t2 |

#### Output data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z |  | t1 |
| 2021-01-01T00:00:10Z | 12 | t1 |
| 2021-01-01T00:00:20Z | -3 | t1 |
| 2021-01-01T00:00:30Z | 10 | t1 |
| 2021-01-01T00:00:40Z | -2 | t1 |
| 2021-01-01T00:00:50Z | -11 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z |  | t2 |
| 2021-01-01T00:00:10Z | -15 | t2 |
| 2021-01-01T00:00:20Z | -7 | t2 |
| 2021-01-01T00:00:30Z | 22 | t2 |
| 2021-01-01T00:00:40Z | -6 | t2 |
| 2021-01-01T00:00:50Z | -12 | t2 |

#### Related

-   [InfluxQL – DIFFERENCE()](/influxdb/v1/query_language/functions/#difference)

[transformations](/flux/v0/tags/transformations/)