Supported Prefixes¶

SI (Decimal) Prefixes¶

Prefix	Name	Base
Q	Quetta	10³⁰
R	Ronna	10²⁷
Y	Yotta	10²⁴
Z	Zetta	10²¹
E	Exa	10¹⁸
P	Peta	10¹⁵
T	Tera	10¹²
G	Giga	10⁹
M	Mega	10⁶
k	Kilo	10³
m	Milli	10^-3
μ	Micro	10^-6
n	Nano	10^-9
p	Pico	10^-12
f	Femto	10^-15
a	Atto	10^-18
z	Zepto	10^-21
y	Yocto	10^-24
r	Ronto	10^-27
q	Quecto	10^-30

IEC (Binary) Prefixes¶

Prefix	Name	Base
Y	Yobi	2⁸⁰
Z	Zebi	2⁷⁰
E	Exbi	2⁶⁰
P	Pedi	2⁵⁰
T	Tebi	2⁴⁰
G	Gibi	2³⁰
M	Mebi	2²⁰
K	Kibi	2¹⁰

Format Specification¶

format_spec     ::=  [[fill]align][sign][#][0][![!]][width][grouping_option][%[-]margin][.precision][type]
fill            ::=  <any character>
align           ::=  "<" | ">" | "=" | "^"
sign            ::=  "+" | "-" | " "
width           ::=  digit+
grouping_option ::=  "_" | ","
precision       ::=  digit+
type            ::=  "e" | "E" | "f" | "F" | "g" | "G" | "h" | "H" | "k" | "K" | "m" | "M" | "n" | "%"

Prefixed-specific fields are defined below. Descriptions of standard fields can be found in the Format Specification Mini-Language documentation.

Prefixed-specific fields¶

Flags¶

Flag	Meaning
`'!'`	Add a single space between number and prefix
`'!!'`	Same as `'!'`, but drop space if there is no prefix

Margin¶

By default, a prefix will be used when the magnitude of that prefix is reached. For example, format(Float(999), '.1h') will result in '999.0' and format(Float(1000), '.1h') will result in '1.0k'.

Margin specifies the percentage to raise or lower these thresholds.

>>> f'{Float(950):%-5.2h}'
'0.95k'

>>> f'{Float(1000):%5.2h}'
'1000.00'

Presentation Types¶

Type Meaning

'h' SI format. Outputs the number with closest divisible SI prefix. (k, M, G, …)

'H' Same as 'h' with precision indicating significant digits.

'k' IEC Format. Outputs the number with closest divisible IEC prefix. (Ki, Mi, Gi, …)

'K' Same as 'k' with precision indicating significant digits.

'm' Short IEC Format. Same as 'k' but only a single character. (K, M, G, …)

'M' Same as 'm' with precision indicating significant digits.

'j' Alias for 'k' - DEPRECATED

'J' Alias for 'm' - DEPRECATED

API Reference¶

class prefixed.Float([x])¶

Subclass of the built-in float class

Key differences:

When a math operation is performed with another real number type (float, int), the result will be a prefixed.Float instance.

Additional presentation types 'h', 'H', 'k', 'K', 'm', and 'M' are supported for f-strings and format().

Type	Meaning
`'h'`	SI format. Outputs the number with closest divisible SI prefix. (k, M, G, …)
`'H'`	Same as `'h'` with precision indicating significant digits.
`'k'`	IEC Format. Outputs the number with closest divisible IEC prefix. (Ki, Mi, Gi, …)
`'K'`	Same as `'k'` with precision indicating significant digits.
`'m'`	Short IEC Format. Same as `'k'` but only a single character. (K, M, G, …)
`'M'`	Same as `'m'` with precision indicating significant digits.

`'j'`	Alias for `'k'` - DEPRECATED
`'J'`	Alias for `'m'` - DEPRECATED

When initializing from strings, SI and IEC prefixes are honored

>>> Float('2k')
Float(2000.0)

>>> Float('2Ki')
Float(2048.0)

An additional format flag ‘!’ is available which adds a space before the prefix
```
>>> f'{Float(3250):!.2h}'
'3.25 k'
```
When the 'H', 'K, or 'M' presentation types are used, precision is treated as the number of significant digits to include. Standard rounding will occur for the final digit.
```
>>> f'{Float(1246):.3h}'
'1.246k'

>>> f'{Float(1246):.3H}'
'1.25k'
```
By default, trailing zeros are removed.
```
>>> f'{Float(1000):.3H}'
'1k'
```
To preserve trailing zeros, include the '#' flag.
```
>>> f'{Float(1000):#.3H}'
'1.00k'
```
An additional field, margin, can be specified which lowers or raises the threshold for for each prefix by the given percentage. Margin is specified before precision with the syntax %[-]digit+.
```
>>> f'{Float(950):.2h}'
'950.00'

>>> f'{Float(950):%-5.2h}'
'0.95k'

>>> f'{Float(1000):%5.2h}'
'1000.00'

>>> f'{Float(1050):%5.2h}'
'1.05k'
```

Overview¶

Prefixed provides an alternative implementation of the built-in float which supports formatted output with SI (decimal) and IEC (binary) prefixes.

>>> from prefixed import Float

>>> f'{Float(3250):.2h}'
'3.25k'

>>> '{:.2h}s'.format(Float(.00001534))
'15.34μs'

>>> '{:.2k}B'.format(Float(42467328))
'40.50MiB'

>>> f'{Float(2048):.2m}B'
'2.00KB'

Because prefixed.Float inherits from the built-in float, it behaves exactly the same in most cases.

When a math operation is performed with another real number type (float, int), the result will be a prefixed.Float instance.

Presentation Types¶

Additional presentation types 'h', 'H', 'k', 'K', 'm', and 'M' are supported for f-strings and format().

Type	Meaning
`'h'`	SI format. Outputs the number with closest divisible SI prefix. (k, M, G, …)
`'H'`	Same as `'h'` with precision indicating significant digits.
`'k'`	IEC Format. Outputs the number with closest divisible IEC prefix. (Ki, Mi, Gi, …)
`'K'`	Same as `'k'` with precision indicating significant digits.
`'m'`	Short IEC Format. Same as `'k'` but only a single character. (K, M, G, …)
`'M'`	Same as `'m'` with precision indicating significant digits.

`'j'`	Alias for `'k'` - DEPRECATED
`'J'`	Alias for `'m'` - DEPRECATED

String Initialization¶

When initializing from strings, SI and IEC prefixes are honored

>>> Float('2k')
Float(2000.0)

>>> Float('2Ki')
Float(2048.0)

Additional Flags¶

An additional format flag ‘!’ is available which adds a space before the prefix

>>> f'{Float(3250):!.2h}'
'3.25 k'

Significant Digits¶

When the 'H', 'K, or 'M' presentation types are used, precision is treated as the number of significant digits to include. Standard rounding will occur for the final digit.

>>> f'{Float(1246):.3h}'
'1.246k'

>>> f'{Float(1246):.3H}'
'1.25k'

By default, trailing zeros are removed.

>>> f'{Float(1000):.3H}'
'1k'

To preserve trailing zeros, include the '#' flag.

>>> f'{Float(1000):#.3H}'
'1.00k'

Adjustable Thresholds¶

An additional field, margin, can be specified which lowers or raises the threshold for for each prefix by the given percentage. Margin is specified before precision with the syntax %[-]digit+.

>>> f'{Float(950):.2h}'
'950.00'

>>> f'{Float(950):%-5.2h}'
'0.95k'

>>> f'{Float(1000):%5.2h}'
'1000.00'

>>> f'{Float(1050):%5.2h}'
'1.05k'