116 lines
3.2 KiB
Markdown
116 lines
3.2 KiB
Markdown
---
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title: kaufmansER() function
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description: >
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`kaufmansER()` computes the Kaufman's Efficiency Ratio (KER) of values in the
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`_value` column for each input table.
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menu:
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flux_v0_ref:
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name: kaufmansER
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parent: universe
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identifier: universe/kaufmansER
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weight: 101
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flux/v0/tags: [transformations]
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introduced: 0.40.0
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---
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<!------------------------------------------------------------------------------
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IMPORTANT: This page was generated from comments in the Flux source code. Any
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edits made directly to this page will be overwritten the next time the
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documentation is generated.
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To make updates to this documentation, update the function comments above the
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function definition in the Flux source code:
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https://github.com/influxdata/flux/blob/master/stdlib/universe/universe.flux#L4501-L4504
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Contributing to Flux: https://github.com/influxdata/flux#contributing
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Fluxdoc syntax: https://github.com/influxdata/flux/blob/master/docs/fluxdoc.md
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------------------------------------------------------------------------------->
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`kaufmansER()` computes the Kaufman's Efficiency Ratio (KER) of values in the
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`_value` column for each input table.
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Kaufman’s Efficiency Ratio indicator divides the absolute value of the Chande
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Momentum Oscillator by 100 to return a value between 0 and 1.
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Higher values represent a more efficient or trending market.
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##### Function type signature
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```js
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(<-tables: stream[A], n: int) => stream[{B with _value: float, _value: float}] where A: Record
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```
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{{% caption %}}
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For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
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{{% /caption %}}
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## Parameters
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### n
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({{< req >}})
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Period or number of points to use in the calculation.
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### tables
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Input data. Default is piped-forward data (`<-`).
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## Examples
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### Compute the Kaufman's Efficiency Ratio
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```js
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import "sampledata"
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sampledata.int()
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|> kaufmansER(n: 3)
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```
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{{< expand-wrapper >}}
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{{% expand "View example input and output" %}}
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#### Input data
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| _time | _value | *tag |
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| -------------------- | ------- | ---- |
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| 2021-01-01T00:00:00Z | -2 | t1 |
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| 2021-01-01T00:00:10Z | 10 | t1 |
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| 2021-01-01T00:00:20Z | 7 | t1 |
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| 2021-01-01T00:00:30Z | 17 | t1 |
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| 2021-01-01T00:00:40Z | 15 | t1 |
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| 2021-01-01T00:00:50Z | 4 | t1 |
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| _time | _value | *tag |
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| -------------------- | ------- | ---- |
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| 2021-01-01T00:00:00Z | 19 | t2 |
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| 2021-01-01T00:00:10Z | 4 | t2 |
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| 2021-01-01T00:00:20Z | -3 | t2 |
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| 2021-01-01T00:00:30Z | 19 | t2 |
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| 2021-01-01T00:00:40Z | 13 | t2 |
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| 2021-01-01T00:00:50Z | 1 | t2 |
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#### Output data
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| _time | _value | *tag |
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| -------------------- | ------------------- | ---- |
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| 2021-01-01T00:00:30Z | 0.76 | t1 |
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| 2021-01-01T00:00:40Z | 0.33333333333333337 | t1 |
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| 2021-01-01T00:00:50Z | 0.13043478260869565 | t1 |
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| _time | _value | *tag |
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| -------------------- | ------------------ | ---- |
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| 2021-01-01T00:00:30Z | 0 | t2 |
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| 2021-01-01T00:00:40Z | 0.2571428571428572 | t2 |
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| 2021-01-01T00:00:50Z | 0.1 | t2 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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