docs-v2/content/flux/v0/stdlib/math/isnan.md

title	description	menu	weight
math.isNaN() function	`math.isNaN()` reports whether `f` is an IEEE 754 "not-a-number" value.	flux_v0_ref name parent identifier math.isNaN math math/isNaN	101

math.isNaN() reports whether f is an IEEE 754 "not-a-number" value.

Function type signature

(f: float) => bool

{{% caption %}} For more information, see Function type signatures. {{% /caption %}}

Parameters

f

({{< req >}}) Value to operate on.

Examples

• Check if a value is a NaN float value
• Use math.isNaN in map

Check if a value is a NaN float value

import "math"

math.isNaN(f: 12.345)// false

Use math.isNaN in map

import "math"

data
    |> map(fn: (r) => ({r with _value: math.isNaN(f: r._value)}))

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Input data

_time	*tag	_value
2021-01-01T00:00:00Z	t1	-2.18
2021-01-01T00:00:10Z	t1	NaN
2021-01-01T00:00:20Z	t1	7.35
2021-01-01T00:00:30Z	t1	NaN
2021-01-01T00:00:40Z	t1	NaN
2021-01-01T00:00:50Z	t1	4.43

_time	*tag	_value
2021-01-01T00:00:00Z	t2	NaN
2021-01-01T00:00:10Z	t2	4.97
2021-01-01T00:00:20Z	t2	-3.75
2021-01-01T00:00:30Z	t2	19.77
2021-01-01T00:00:40Z	t2	NaN
2021-01-01T00:00:50Z	t2	1.86

Output data

_time	_value	*tag
2021-01-01T00:00:00Z	false	t1
2021-01-01T00:00:10Z	true	t1
2021-01-01T00:00:20Z	false	t1
2021-01-01T00:00:30Z	true	t1
2021-01-01T00:00:40Z	true	t1
2021-01-01T00:00:50Z	false	t1

_time	_value	*tag
2021-01-01T00:00:00Z	true	t2
2021-01-01T00:00:10Z	false	t2
2021-01-01T00:00:20Z	false	t2
2021-01-01T00:00:30Z	false	t2
2021-01-01T00:00:40Z	true	t2
2021-01-01T00:00:50Z	false	t2

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