---
title: experimental.quantile() function
description: experimental.quantile() returns non-null records with values in the _value column that fall within the specified quantile or represent the specified quantile.
url: https://docs.influxdata.com/flux/v0/stdlib/experimental/quantile/
estimated_tokens: 2632
product: Flux
version: v0
---

# experimental.quantile() function

-   Flux 0.107.0+
-   View InfluxDB support

`experimental.quantile()` is [subject to change at any time](/flux/v0/stdlib/experimental/#experimental-packages-are-subject-to-change).

`experimental.quantile()` returns non-null records with values in the `_value` column that fall within the specified quantile or represent the specified quantile.

The `_value` column must contain float values.

## Computation methods and behavior

`experimental.quantile()` behaves like an **aggregate function** or a **selector function** depending on the `method` parameter. The following computation methods are available:

##### estimate\_tdigest

An aggregate method that uses a [t-digest data structure](https://github.com/tdunning/t-digest) to compute an accurate quantile estimate on large data sources. When used, `experimental.quantile()` outputs non-null records with values that fall within the specified quantile.

##### exact\_mean

An aggregate method that takes the average of the two points closest to the quantile value. When used, `experimental.quantile()` outputs non-null records with values that fall within the specified quantile.

##### exact\_selector

A selector method that returns the data point for which at least `q` points are less than. When used, `experimental.quantile()` outputs the non-null record with the value that represents the specified quantile.

##### Function type signature

```js
(
    <-tables: stream[{A with _value: float}],
    q: float,
    ?compression: float,
    ?method: string,
) => stream[{A with _value: float}]
```

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

## Parameters

### q

(Required) Quantile to compute (`[0 - 1]`).

### method

Computation method. Default is `estimate_tdigest`.

**Supported methods**:

-   estimate\_tdigest
-   exact\_mean
-   exact\_selector

### compression

Number of centroids to use when compressing the dataset. Default is `1000.0`.

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

### tables

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

## Examples

-   [Return values in the 50th percentile of each input table](#return-values-in-the-50th-percentile-of-each-input-table)
-   [Return a value representing the 50th percentile of each input table](#return-a-value-representing-the-50th-percentile-of-each-input-table)

### Return values in the 50th percentile of each input table

```js
import "experimental"
import "sampledata"

sampledata.float()
    |> experimental.quantile(q: 0.5)
```

[](#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 |

### Return a value representing the 50th percentile of each input table

```js
import "experimental"
import "sampledata"

sampledata.float()
    |> experimental.quantile(q: 0.5, 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 percentile and quantile values](/influxdb/v2/query-data/flux/percentile-quantile/)
-   [quantile() function](/flux/v0/stdlib/universe/quantile/)
-   [InfluxQL – PERCENTILE()](/influxdb/v1/query_language/functions/#percentile)

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