| [Pillow](http://pillow.readthedocs.org/) | Pillow is the 'friendly PIL fork' by Alex Clark and Contributors. PIL is the Python Imaging Library by Fredrik Lundh and Contributors. |
| [pluggy](https://github.com/pytest-dev/pluggy) | Plugin and hook calling mechanisms for python. |
| [pudb](https://pypi.python.org/pypi/pudb) | PuDB is a full-screen, console-based visual debugger for Python. |
| [pybtex](https://pypi.python.org/pypi/pybtex) | A BibTeX-compatible bibliography processor in Python. |
| [PyDispatcher](https://pypi.python.org/pypi/PyDispatcher) | Multi-producer-multi-consumer signal dispatching mechanism. |
| [pymatgen](https://pypi.python.org/pypi/pymatgen) | Python Materials Genomics is a robust materials analysis code that defines core object representations for structures and molecules with support for many electronic structure codes. It is currently the core analysis code powering the Materials Project (https://www.materialsproject.org). |
| [pyparsing](http://pyparsing.wikispaces.com) | The pyparsing module provides a library of classes that client code uses to construct the grammar directly in Python code. |
| PyQt | |
| [PyQt5](http://www.riverbankcomputing.co.uk/software/pyqt) | PyQt5 is a set of Python bindings for v5 of the Qt application framework from The Qt Company. |
| [pyspark](https://pypi.python.org/pypi/pyspark) | Apache Spark Python API |
| [pytest](http://pytest.org) | Simple powerful testing with Python |
| [python-dateutil](https://github.com/dateutil/dateutil) | Useful extensions to the standard Python datetime features. |
| [pytz](http://pytz.sourceforge.net/) | pytz brings the Olson tz database into Python. This library allows accurate and cross platform timezone calculations using Python 2.4 or higher. |