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https://github.com/KenKundert/quantiphy

Physical quantities
https://github.com/KenKundert/quantiphy

python quantiphy quantities si-prefixes si-units unit-conversions units

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Physical quantities

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README 

        
QuantiPhy — Physical Quantities

===============================



|downloads| |build status| |coverage| |rtd status| |pypi version| |anaconda version| |python version|



| Author: Ken Kundert

| Version: 2.20

| Released: 2024-04-27

|



What?

-----



*QuantiPhy* is a Python library that offers support for physical quantities.  

A quantity is the pairing of a number and a unit of measure that indicates the 

amount of some measurable thing.  *QuantiPhy* provides quantity objects that 

keep the units with the number, making it easy to share them as single object.  

They subclass float and so can be used anywhere a real number is appropriate.



Why?

----



*QuantiPhy* naturally supports SI scale factors, which are widely used in 

science and engineering. SI scale factors make it possible to cleanly represent 

both very large and very small quantities in a form that is both easy to read 

and write.  While generally better for humans, no general programming language 

provides direct support for reading or writing quantities with SI scale factors, 

making it difficult to write numerical software that communicates effectively 

with people.  *QuantiPhy* addresses this deficiency, making it natural and 

simple to both input and output physical quantities.



Features

--------



- Flexibly reads amounts with units and SI scale factors.

- Quantities subclass the *float* class and so can be used as conventional 

  numbers.

- Generally includes the units when printing or converting to strings and by 

  default employs SI scale factors.

- Flexible unit conversion and scaling is supported to make it easy to convert 

  to or from any required form.

- Supports the binary scale factors (*Ki*, *Mi*, etc.) along with the normal SI 

  scale factors (*k*, *M*, etc.).

- When a quantity is created from a string, the actual digits specified can be 

  used in any output, eliminating any loss of precision.



Alternatives

------------



There are a considerable number of Python packages dedicated to units and 

quantities (`alternatives `_).  

However, as a rule, they focus on the units rather than the scale factors. In 

particular, they build a system of units that you are expected to use throughout 

your calculations.  These packages demand a high level of commitment from their 

users and in turn provide unit consistency and built-in unit conversions.



In contrast, *QuantiPhy* treats units basically as documentation.  They are 

simply strings that are attached to quantities largely so they can be presented 

to the user when the values are printed. As such, *QuantiPhy* is a light-weight 

package that demands little from the user.  It is used when inputting and 

outputting values, and then only when it provides value.  As a result, it 

provides a simplicity in use that cannot be matched by the other packages.



In addition, these alternative packages generally build their unit systems upon 

the `SI base units `_, which tends 

to restrict usage to physical quantities with static conversion factors.  They 

are less suited to non-physical quantities or conversion factors that change 

dynamically, such as with currencies.  *QuantiPhy* gracefully handles all of 

these cases.



Quick Start

-----------



You can find the documentation on `ReadTheDocs

`_.  Install with::



   pip3 install --user quantiphy



Requires Python 3.6 or newer.  If you using an earlier version of Python,

install version 2.10 of *QuantiPhy*.



You can find the full documentation `here `_.



You use *Quantity* to convert numbers and units in various forms to quantities:



.. code-block:: python



   >>> from quantiphy import Quantity



   >>> Tclk = Quantity(10e-9, 's')

   >>> print(Tclk)

   10 ns



   >>> Fhy = Quantity('1420.405751786 MHz')

   >>> print(Fhy)

   1.4204 GHz



   >>> Rsense = Quantity('1e-4Ω')

   >>> print(Rsense)

   100 uΩ



   >>> cost = Quantity('$11_200_000')

   >>> print(cost)

   $11.2M



   >>> Tboil = Quantity('212 °F', scale='°C')

   >>> print(Tboil)

   100 °C



Once you have a quantity, there are a variety of ways of accessing aspects of 

the quantity:



.. code-block:: python



   >>> Tclk.real

   1e-08



   >>> float(Fhy)

   1420405751.786



   >>> 2*cost

   22400000.0



   >>> Rsense.units

   'Ω'



   >>> str(Tboil)

   '100 °C'



You can use the *render* method to flexibly convert the quantity to a string:



.. code-block:: python



   >>> Tclk.render()

   '10 ns'



   >>> Tclk.render(show_units=False)

   '10n'



   >>> Tclk.render(form='eng', show_units=False)

   '10e-9'



   >>> Fhy.render(prec=8)

   '1.42040575 GHz'



   >>> Tboil.render(scale='°F')

   '212 °F'



The *fixed* method is a variant that specializes in rendering numbers without 

scale factors or exponents:



.. code-block:: python



   >>> cost.fixed(prec=2, show_commas=True, strip_zeros=False)

   '$11,200,000.00'



You can use the string format method or the new format strings to flexibly 

incorporate quantity values into strings:



.. code-block:: python



   >>> f'{Fhy}'

   '1.4204 GHz'



   >>> f'{Fhy:.6}'

   '1.420406 GHz'



   >>> f'❬{Fhy:<15.6}❭'

   '❬1.420406 GHz   ❭'



   >>> f'❬{Fhy:>15.6}❭'

   '❬   1.420406 GHz❭'



   >>> f'{cost:#,.2P}'

   '$11,200,000.00'



   >>> f'Boiling point of water: {Tboil:s}'

   'Boiling point of water: 100 °C'



   >>> f'Boiling point of water: {Tboil:s°F}'

   'Boiling point of water: 212 °F'



*QuantiPhy* has many more features and capabilities. For more information, view 

the `documentation `_.



.. |downloads| image:: https://pepy.tech/badge/quantiphy/month

    :target: https://pepy.tech/project/quantiphy



.. |rtd status| image:: https://img.shields.io/readthedocs/quantiphy.svg

   :target: https://quantiphy.readthedocs.io/en/latest/?badge=latest



.. |build status| image:: https://github.com/KenKundert/quantiphy/actions/workflows/build.yaml/badge.svg

    :target: https://github.com/KenKundert/quantiphy/actions/workflows/build.yaml



.. |coverage| image:: https://coveralls.io/repos/github/KenKundert/quantiphy/badge.svg?branch=master

    :target: https://coveralls.io/github/KenKundert/quantiphy?branch=master



.. |pypi version| image:: https://img.shields.io/pypi/v/quantiphy.svg

    :target: https://pypi.python.org/pypi/quantiphy



.. |anaconda version| image:: https://anaconda.org/conda-forge/quantiphy/badges/version.svg

    :target: https://anaconda.org/conda-forge/quantiphy



.. |python version| image:: https://img.shields.io/pypi/pyversions/quantiphy.svg

    :target: https://pypi.python.org/pypi/quantiphy/