114 lines
2.8 KiB
Markdown
114 lines
2.8 KiB
Markdown
---
|
|
title: experimental.count() function
|
|
description: >
|
|
`experimental.count()` returns the number of records in each input table.
|
|
menu:
|
|
flux_v0_ref:
|
|
name: experimental.count
|
|
parent: experimental
|
|
identifier: experimental/count
|
|
weight: 101
|
|
flux/v0/tags: [transformations, aggregates]
|
|
introduced: 0.107.0
|
|
---
|
|
|
|
<!------------------------------------------------------------------------------
|
|
|
|
IMPORTANT: This page was generated from comments in the Flux source code. Any
|
|
edits made directly to this page will be overwritten the next time the
|
|
documentation is generated.
|
|
|
|
To make updates to this documentation, update the function comments above the
|
|
function definition in the Flux source code:
|
|
|
|
https://github.com/influxdata/flux/blob/master/stdlib/experimental/experimental.flux#L686-L686
|
|
|
|
Contributing to Flux: https://github.com/influxdata/flux#contributing
|
|
Fluxdoc syntax: https://github.com/influxdata/flux/blob/master/docs/fluxdoc.md
|
|
|
|
------------------------------------------------------------------------------->
|
|
|
|
`experimental.count()` returns the number of records in each input table.
|
|
|
|
The count is returned in the `_value` column and counts both null and non-null records.
|
|
|
|
#### Counts on empty tables
|
|
`experimental.count()` returns 0 for empty tables.
|
|
To keep empty tables in your data, set the following parameters when using
|
|
the following functions:
|
|
|
|
```
|
|
filter(onEmpty: "keep")
|
|
window(createEmpty: true)
|
|
aggregateWindow(createEmpty: true)
|
|
```
|
|
|
|
##### Function type signature
|
|
|
|
```js
|
|
(<-tables: stream[{A with _value: B}]) => stream[{A with _value: int}]
|
|
```
|
|
|
|
{{% caption %}}
|
|
For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
|
|
{{% /caption %}}
|
|
|
|
## Parameters
|
|
|
|
### tables
|
|
|
|
Input data. Default is piped-forward data (`<-`).
|
|
|
|
|
|
|
|
|
|
## Examples
|
|
|
|
### Count the number of rows in a table
|
|
|
|
```js
|
|
import "experimental"
|
|
import "sampledata"
|
|
|
|
sampledata.int()
|
|
|> experimental.count()
|
|
|
|
```
|
|
|
|
{{< expand-wrapper >}}
|
|
{{% expand "View example input and output" %}}
|
|
|
|
#### 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
|
|
|
|
| *tag | _value |
|
|
| ---- | ------- |
|
|
| t1 | 6 |
|
|
|
|
| *tag | _value |
|
|
| ---- | ------- |
|
|
| t2 | 6 |
|
|
|
|
{{% /expand %}}
|
|
{{< /expand-wrapper >}}
|