## Pint: makes units easy

Pint is a Python package to define, operate and manipulate physical quantities: the product of a numerical value and a unit of measurement. It allows arithmetic operations between them and conversions from and to different units.

It is distributed with a comprehensive list of physical units, prefixes
and constants. Due to its modular design, you can extend (or even rewrite!)
the complete list without changing the source code. It supports a lot of
numpy mathematical operations **without monkey patching or wrapping numpy**.

It has a complete test coverage. It runs in Python 3.8+ with no other dependency. It is licensed under BSD.

It is extremely easy and natural to use:

```
>>> import pint
>>> ureg = pint.UnitRegistry()
>>> 3 * ureg.meter + 4 * ureg.cm
<Quantity(3.04, 'meter')>
```

and you can make good use of numpy if you want:

```
>>> import numpy as np
>>> [3, 4] * ureg.meter + [4, 3] * ureg.cm
<Quantity([ 3.04 4.03], 'meter')>
>>> np.sum(_)
<Quantity(7.07, 'meter')>
```

### Quick Installation

To install Pint, simply:

`$ pip install pint`

or utilizing conda, with the conda-forge channel:

`$ conda install -c conda-forge pint`

and then simply enjoy it!

### Documentation

Full documentation is available at http://pint.readthedocs.org/

### Command-line converter

A command-line script pint-convert provides a quick way to convert between units or get conversion factors.

### Design principles

Although there are already a few very good Python packages to handle physical quantities, no one was really fitting my needs. Like most developers, I programmed Pint to scratch my own itches.

**Unit parsing**: prefixed and pluralized forms of units are recognized without
explicitly defining them. In other words: as the prefix *kilo* and the unit
*meter* are defined, Pint understands *kilometers*. This results in a much
shorter and maintainable unit definition list as compared to other packages.

**Standalone unit definitions**: units definitions are loaded from a text file
which is simple and easy to edit. Adding and changing units and their
definitions does not involve changing the code.

**Advanced string formatting**: a quantity can be formatted into string using
PEP 3101 syntax. Extended conversion flags are given to provide symbolic,
LaTeX and pretty formatting. Unit name translation is available if Babel is
installed.

**Free to choose the numerical type**: You can use any numerical type
(fraction, float, decimal, numpy.ndarray, etc). NumPy is not required
but supported.

**Awesome NumPy integration**: When you choose to use a NumPy ndarray, its methods and
ufuncs are supported including automatic conversion of units. For example
numpy.arccos(q) will require a dimensionless q and the units of the output
quantity will be radian.

**Uncertainties integration**: transparently handles calculations with
quantities with uncertainties (like 3.14±0.01 meter) via the uncertainties
package.

**Handle temperature**: conversion between units with different reference
points, like positions on a map or absolute temperature scales.

**Dependency free**: it depends only on Python and its standard library. It interacts with other packages
like numpy and uncertainties if they are installed

**Pandas integration**: Thanks to Pandas Extension Types it is now possible to use Pint with Pandas. Operations on DataFrames and between columns are units aware, providing even more convenience for users of Pandas DataFrames. For full details, see the pint-pandas Jupyter notebook.

Pint is maintained by a community of scientists, programmers and enthusiasts around the world. See AUTHORS for a complete list.

To review an ordered list of notable changes for each version of a project, see CHANGES