141 lines
3.9 KiB
Markdown
141 lines
3.9 KiB
Markdown
---
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title: fill() function
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description: The `fill()` function replaces all null values in an input stream and replace them with a non-null value.
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aliases:
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- /influxdb/v2.0/reference/flux/functions/transformations/fill
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- /influxdb/v2.0/reference/flux/functions/built-in/transformations/fill/
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- /influxdb/v2.0/reference/flux/stdlib/built-in/transformations/fill/
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- /influxdb/cloud/reference/flux/stdlib/built-in/transformations/fill/
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menu:
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flux_0_x_ref:
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name: fill
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parent: universe
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weight: 102
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flux/v0.x/tags: [transformations]
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related:
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- /{{< latest "influxdb" >}}/query-data/flux/fill/
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- /{{< latest "influxdb" "v1" >}}/query_language/explore-data/#group-by-time-intervals-and-fill, InfluxQL – FILL
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introduced: 0.14.0
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---
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The `fill()` function replaces all null values in an input stream with a non-null value.
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The output stream is the same as the input stream with all null values replaced in the specified column.
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```js
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fill(column: "_value", value: 0.0)
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// OR
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fill(column: "_value", usePrevious: true)
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```
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## Parameters
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### column {data-type="string"}
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The column in which to replace null values. Defaults to `"_value"`.
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### value {data-type="string, bool, int, uint, float, duration, time"}
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The constant value to use in place of nulls.
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The value type must match the value type of the `column`.
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### usePrevious {data-type="bool"}
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When `true`, assigns the value set in the previous non-null row.
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{{% note %}}
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Cannot be used with `value`.
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{{% /note %}}
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### tables {data-type="stream of tables"}
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Input data.
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Default is piped-forward data ([`<-`](/flux/v0.x/spec/expressions/#pipe-expressions)).
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## Examples
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{{% flux/sample-example-intro plural=true %}}
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- [Fill null values with a specified non-null value](#fill-null-values-with-a-specified-non-null-value)
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- [Fill null values with the previous non-null value](#fill-null-values-with-the-previous-non-null-value)
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#### Fill null values with a specified non-null value
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```js
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import "sampledata"
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sampledata.float(includeNull: true)
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|> fill(value: 0.0)
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```
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{{< expand-wrapper >}}
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{{% expand "View input and output" %}}
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{{< flex >}}
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{{% flex-content %}}
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##### Input data
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{{% flux/sample "float" true %}}
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{{% /flex-content %}}
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{{% flex-content %}}
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##### Output data
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| _time | tag | _value |
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| :------------------- | :-- | -----: |
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| 2021-01-01T00:00:00Z | t1 | -2.18 |
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| 2021-01-01T00:00:10Z | t1 | 0.0 |
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| 2021-01-01T00:00:20Z | t1 | 7.35 |
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| 2021-01-01T00:00:30Z | t1 | 0.0 |
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| 2021-01-01T00:00:40Z | t1 | 0.0 |
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| 2021-01-01T00:00:50Z | t1 | 4.43 |
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| _time | tag | _value |
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| :------------------- | :-- | -----: |
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| 2021-01-01T00:00:00Z | t2 | 0.0 |
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| 2021-01-01T00:00:10Z | t2 | 4.97 |
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| 2021-01-01T00:00:20Z | t2 | -3.75 |
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| 2021-01-01T00:00:30Z | t2 | 19.77 |
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| 2021-01-01T00:00:40Z | t2 | 0.0 |
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| 2021-01-01T00:00:50Z | t2 | 1.86 |
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{{% /flex-content %}}
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{{< /flex >}}
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{{% /expand %}}
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{{< /expand-wrapper >}}
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#### Fill null values with the previous non-null value
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```js
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import "sampledata"
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sampledata.float(includeNull: true)
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|> fill(usePrevious: true)
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```
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{{% expand "View input and output" %}}
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{{< flex >}}
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{{% flex-content %}}
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##### Input data
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{{% flux/sample "float" true %}}
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{{% /flex-content %}}
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{{% flex-content %}}
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##### Output data
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| _time | tag | _value |
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| :------------------- | :-- | -----: |
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| 2021-01-01T00:00:00Z | t1 | -2.18 |
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| 2021-01-01T00:00:10Z | t1 | -2.18 |
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| 2021-01-01T00:00:20Z | t1 | 7.35 |
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| 2021-01-01T00:00:30Z | t1 | 7.35 |
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| 2021-01-01T00:00:40Z | t1 | 7.35 |
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| 2021-01-01T00:00:50Z | t1 | 4.43 |
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| _time | tag | _value |
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| :------------------- | :-- | -----: |
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| 2021-01-01T00:00:00Z | t2 | |
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| 2021-01-01T00:00:10Z | t2 | 4.97 |
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| 2021-01-01T00:00:20Z | t2 | -3.75 |
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| 2021-01-01T00:00:30Z | t2 | 19.77 |
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| 2021-01-01T00:00:40Z | t2 | 19.77 |
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| 2021-01-01T00:00:50Z | t2 | 1.86 |
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{{% /flex-content %}}
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{{< /flex >}}
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{{% /expand %}}
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