docs-v2/content/flux/v0/stdlib/universe/top.md

title	description	menu	weight	flux/v0/tags	introduced
top() function	`top()` sorts each input table by specified columns and keeps the top `n` records in each table.	flux_v0_ref name parent identifier top universe universe/top	101	transformations selectors	0.7.0

top() sorts each input table by specified columns and keeps the top n records in each table.

Note: top() drops empty tables.

Function type signature

(<-tables: stream[A], n: int, ?columns: [string]) => stream[A] where A: Record

{{% caption %}} For more information, see Function type signatures. {{% /caption %}}

Parameters

n

({{< req >}}) Number of rows to return from each input table.

columns

List of columns to sort by. Default is ["_value"].

Sort precedence is determined by list order (left to right).

tables

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

Examples

Return rows with the three highest values in each input table

import "sampledata"

sampledata.int()
    |> top(n: 3)

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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
2021-01-01T00:00:30Z	17	t1
2021-01-01T00:00:40Z	15	t1
2021-01-01T00:00:10Z	10	t1

_time	_value	*tag
2021-01-01T00:00:00Z	19	t2
2021-01-01T00:00:30Z	19	t2
2021-01-01T00:00:40Z	13	t2

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