---
title: covariance() function
description: >
  `covariance()` computes the covariance between two columns.
menu:
  flux_v0_ref:
    name: covariance
    parent: universe
    identifier: universe/covariance
weight: 101
flux/v0/tags: [transformations, aggregates]
introduced: 0.7.0
---

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`covariance()` computes the covariance between two columns.



##### Function type signature

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

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

### columns
({{< req >}})
List of two columns to operate on.



### pearsonr

Normalize results to the Pearson R coefficient. Default is `false`.



### valueDst

Column to store the result in. Default is `_value`.



### tables

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




## Examples

### Calculate the covariance between two columns

```js
data
    |> covariance(columns: ["x", "y"])

```

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#### Input data

| _time                | x  | y    |
| -------------------- | -- | ---- |
| 2021-01-01T00:00:00Z | 0  | 0    |
| 2021-01-01T00:00:12Z | 1  | 0.5  |
| 2021-01-01T00:00:24Z | 4  | 8    |
| 2021-01-01T00:00:36Z | 9  | 40.5 |
| 2021-01-01T00:00:48Z | 16 | 128  |


#### Output data

| _value  |
| ------- |
| 345.75  |

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