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

title	description	menu	weight	flux/v0/tags	introduced
count() function	`count()` returns the number of records in each input table.	flux_v0_ref name parent identifier count universe universe/count	101	transformations aggregates	0.7.0

count() returns the number of records in each input table.

The function counts both null and non-null records.

Empty tables

count() returns 0 for empty tables. To keep empty tables in your data, set the following parameters for the following functions:

Function	Parameter
filter()	onEmpty: "keep"
window()	createEmpty: true
aggregateWindow()	createEmpty: true

Function type signature

(<-tables: stream[A], ?column: string) => stream[B] where A: Record, B: Record

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Parameters

column

Column to count values in and store the total count.

tables

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

Examples

• Count the number of records in each input table
• Count the number of records with a specific value

Count the number of records in each input table

import "sampledata"

sampledata.string()
    |> count()

Count the number of records with a specific value

1. Use filter() to filter data by the specific value you want to count.
2. Use count() to count the number of rows in the table.

import "sampledata"

data =
    sampledata.int()
        |> filter(fn: (r) => r._value > 10)

data
    |> count()

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Input data

_time	_value	*tag
2021-01-01T00:00:30Z	17	t1
2021-01-01T00:00:40Z	15	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

Output data

*tag	_value
t1	2

*tag	_value
t2	3

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