---
title: median() function
description: median() returns the median _value of an input table or all non-null records in the input table with values that fall within the 0.5 quantile (50th percentile).
url: https://docs.influxdata.com/flux/v0/stdlib/universe/median/
estimated_tokens: 2234
product: Flux
version: v0
---

# median() function

-   Flux 0.7.0+
-   View InfluxDB support

`median()` returns the median `_value` of an input table or all non-null records in the input table with values that fall within the 0.5 quantile (50th percentile).

### Function behavior

`median()` acts as an aggregate or selector transformation depending on the specified `method`.

-   **Aggregate**: When using the `estimate_tdigest` or `exact_mean` methods, `median()` acts as an aggregate transformation and outputs the average of non-null records with values that fall within the 0.5 quantile (50th percentile).
-   **Selector**: When using the `exact_selector` method, `meidan()` acts as a selector selector transformation and outputs the non-null record with the value that represents the 0.5 quantile (50th percentile).

##### Function type signature

```js
(<-tables: stream[A], ?column: string, ?compression: float, ?method: string) => stream[A] where A: Record
```

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

## Parameters

### column

Column to use to compute the median. Default is `_value`.

### method

Computation method. Default is `estimate_tdigest`.

**Available methods**:

-   **estimate\_tdigest**: Aggregate method that uses a [t-digest data structure](https://github.com/tdunning/t-digest) to compute an accurate median estimate on large data sources.
-   **exact\_mean**: Aggregate method that takes the average of the two points closest to the median value.
-   **exact\_selector**: Selector method that returns the row with the value for which at least 50% of points are less than.

### compression

Number of centroids to use when compressing the dataset. Default is `0.0`.

A larger number produces a more accurate result at the cost of increased memory requirements.

### tables

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

## Examples

-   [Use median as an aggregate transformation](#use-median-as-an-aggregate-transformation)
-   [Use median as a selector transformation](#use-median-as-a-selector-transformation)

### Use median as an aggregate transformation

```js
import "sampledata"

sampledata.float()
    |> median()
```

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

View example input and output

#### Input data

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | t1 | -2.18 |
| 2021-01-01T00:00:10Z | t1 | 10.92 |
| 2021-01-01T00:00:20Z | t1 | 7.35 |
| 2021-01-01T00:00:30Z | t1 | 17.53 |
| 2021-01-01T00:00:40Z | t1 | 15.23 |
| 2021-01-01T00:00:50Z | t1 | 4.43 |

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | t2 | 19.85 |
| 2021-01-01T00:00:10Z | t2 | 4.97 |
| 2021-01-01T00:00:20Z | t2 | -3.75 |
| 2021-01-01T00:00:30Z | t2 | 19.77 |
| 2021-01-01T00:00:40Z | t2 | 13.86 |
| 2021-01-01T00:00:50Z | t2 | 1.86 |

#### Output data

| *tag | _value |
| --- | --- |
| t1 | 9.135 |

| *tag | _value |
| --- | --- |
| t2 | 9.415 |

### Use median as a selector transformation

```js
import "sampledata"

sampledata.float()
    |> median(method: "exact_selector")
```

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

View example input and output

#### Input data

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | t1 | -2.18 |
| 2021-01-01T00:00:10Z | t1 | 10.92 |
| 2021-01-01T00:00:20Z | t1 | 7.35 |
| 2021-01-01T00:00:30Z | t1 | 17.53 |
| 2021-01-01T00:00:40Z | t1 | 15.23 |
| 2021-01-01T00:00:50Z | t1 | 4.43 |

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | t2 | 19.85 |
| 2021-01-01T00:00:10Z | t2 | 4.97 |
| 2021-01-01T00:00:20Z | t2 | -3.75 |
| 2021-01-01T00:00:30Z | t2 | 19.77 |
| 2021-01-01T00:00:40Z | t2 | 13.86 |
| 2021-01-01T00:00:50Z | t2 | 1.86 |

#### Output data

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:20Z | t1 | 7.35 |

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:10Z | t2 | 4.97 |

#### Related

-   [Find median values](/influxdb/v2/query-data/flux/median/)
-   [InfluxQL – MEDIAN()](/influxdb/v1/query_language/functions/#median)

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