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.

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

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'