docs-v2/content/flux/v0.x/stdlib/universe/relativestrengthindex.md

title	description	aliases	menu	weight	flux/v0.x/tags	related	introduced
relativeStrengthIndex() function	The `relativeStrengthIndex()` function measures the relative speed and change of values in an input table.	/influxdb/v2.0/reference/flux/functions/built-in/transformations/aggregates/relativestrengthindex/ /influxdb/v2.0/reference/flux/stdlib/built-in/transformations/aggregates/relativestrengthindex/ /influxdb/v2.0/reference/flux/stdlib/built-in/transformations/relativestrengthindex/ /influxdb/cloud/reference/flux/stdlib/built-in/transformations/relativestrengthindex/	flux_0_x_ref name parent relativeStrengthIndex universe	102	transformations	/flux/v0.x/stdlib/universe/movingaverage/ /flux/v0.x/stdlib/universe/timedmovingaverage/ /flux/v0.x/stdlib/universe/exponentialmovingaverage/ /{{< latest "influxdb" "v1" >}}/query_language/functions/#relative-strength-index, InfluxQL RELATIVE_STRENGTH_INDEX()	0.38.0

The relativeStrengthIndex() function measures the relative speed and change of values in an input table.

relativeStrengthIndex(
    n: 5,
    columns: ["_value"],
)

Relative strength index rules

• The general equation for calculating a relative strength index (RSI) is RSI = 100 - (100 / (1 + (AVG GAIN / AVG LOSS))).
• For the first value of the RSI, AVG GAIN and AVG LOSS are averages of the n period.
• For subsequent calculations:
  • AVG GAIN = ((PREVIOUS AVG GAIN) * (n - 1)) / n
  • AVG LOSS = ((PREVIOUS AVG LOSS) * (n - 1)) / n
• relativeStrengthIndex() ignores null values.

Parameters

n

({{< req >}}) The number of values to use to calculate the RSI.

columns

Columns to operate on. Default is ["_value"].

tables

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

Output tables

For each input table with x rows, relativeStrengthIndex() outputs a table with x - n rows.

Examples

{{% flux/sample-example-intro %}}

Calculate a three point relative strength index

import "sampledata"

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

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Input data

{{% flux/sample "int" %}}

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Output data

_time	tag	_value
2021-01-01T00:00:30Z	t1	84.375
2021-01-01T00:00:40Z	t1	73.97260273972603
2021-01-01T00:00:50Z	t1	36.672325976230894

_time	tag	_value
2021-01-01T00:00:30Z	t2	70.27027027027026
2021-01-01T00:00:40Z	t2	59.42857142857142
2021-01-01T00:00:50Z	t2	40.625
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