Work with floats

A float type represents a IEEE-754 64-bit floating-point number.

Type name: float

Float syntax

A float literal contains a decimal integer, a decimal point, and a decimal fraction.


Scientific notation

Flux does not support scientific notation float literal syntax. However, you can use float() to convert a scientific notation string into a float type.

// Error: error @1:8-1:9: undefined identifier e

float(v: "1.23456e+78")
// Returns 1.23456e+78 (float)


Flux does not support infinite float literal syntax (+Inf and -Inf). However, you can use float() to convert a infinite string into a float type.

// Error: error @1:2-1:5: undefined identifier Inf

float(v: "+Inf")
// Returns +Inf (float)

Not a Number

Flux does not support Not a Number (NaN) float literal syntax. However, you can use float() to convert a NaN string into a float type.

// Error: error @1:2-1:5: undefined identifier NaN

float(v: "NaN")
// Returns NaN (float)

Convert data types to floats

Use the float() function to convert the following basic types to floats:

  • string: must be a numeric string or scientific notation
  • bool: true converts to 1.0, false converts to 0.0
  • int
  • uint
float(v: "1.23")
// 1.23

float(v: true)
// Returns 1.0

float(v: 123)
// Returns 123.0

Convert columns to floats

Flux lets you iterate over rows in a stream of tables and convert columns to floats.

To convert the _value column to floats, use the toFloat() function.

toFloat() only operates on the _value column.

    |> toFloat()
Given the following input data:
_time_value (int)
The example above returns:
_time_value (float)

To convert any column to floats:

  1. Use map() to iterate over and rewrite rows.
  2. Use float() to convert columns values to floats.
    |> map(fn: (r) => ({ r with index: float(v: r.index) }))
Given the following input data:
_timeindex (int)
The example above returns:
_timeindex (float)

Operate on floats

Perform arithmetic operations on floats

To perform operations like adding, subtracting, multiplying, or dividing float values, use Flux arithmetic operators. Operands must be the same type.

1.23 + 45.67
// Returns 46.9

1.23 - 45.67
// Returns -44.440000000000005

float(v: "12345e+67") * 100.0
// Returns 1.2345000000000001e+73

144.0 / 12.0
// Returns 12.0

10.0 ^ 2.0
// Returns 100.0

Inherent rounding errors in floating-point arithmetic

To fit an infinite number of real values into a finite number of bits, computer systems must round floating-point values in arithmetic operations. This results in small rounding errors in some operations.

Compare float values

Use Flux comparison operators to compare float values. Operands must be the same type. The operation returns a float.

12345600.0 == float(v: "1.23456e+07")
// Returns true

1.2 > -2.1
// Returns true

Round float values

  1. Import the math package.
  2. Use math.round() to round to the nearest whole number.
import "math"

math.round(x: 1.54)
// Returns 2.0

Flux math package

Use the math package to perform operations on float values.

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