https://github.com/has2k1/plydata

A grammar for data manipulation in Python
https://github.com/has2k1/plydata

data-manipulation pandas python

Last synced: about 2 months ago
JSON representation

A grammar for data manipulation in Python

• Host: GitHub
• URL: https://github.com/has2k1/plydata
• Owner: has2k1
• License: bsd-3-clause
• Created: 2017-04-11T04:17:16.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2023-09-19T20:24:47.000Z (about 1 year ago)
• Last Synced: 2024-07-19T22:28:00.526Z (2 months ago)
• Topics: data-manipulation, pandas, python
• Language: Python
• Homepage: https://plydata.readthedocs.io/en/stable/
• Size: 807 KB
• Stars: 275
• Watchers: 18
• Forks: 11
• Open Issues: 10
• Metadata Files:
  • Readme: README.rst
  • License: LICENSE

Awesome Lists containing this project

README

        
#######

plydata

#######

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

Latest Release               |release|_

License                      |license|_

Build Status                 |buildstatus|_

Coverage                     |coverage|_

Documentation (Dev)          |documentation|_

Documentation (Release)      |documentation_stable|_

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

plydata is a library that provides a grammar for data manipulation.

The grammar consists of verbs that can be applied to pandas

dataframes or database tables. It is based on the R packages

`dplyr`_, `tidyr`_ and `forcats`_. plydata uses the ``>>`` operator

as a pipe symbol, alternatively there is the ``ply(data, *verbs)``

function that you can use instead of ``>>``.

At present the only supported data store is the *pandas* dataframe.

We expect to support *sqlite* and maybe *postgresql* and *mysql*.

Installation

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

plydata **only** supports Python 3.

**Official version**

.. code-block:: console

   $ pip install plydata

**Development version**

.. code-block:: console

   $ pip install git+https://github.com/has2k1/plydata.git@master

Example

-------

.. code-block:: python

    import pandas as pd

    import numpy as np

    from plydata import define, query, if_else, ply

    # NOTE: query is the equivalent of dplyr's filter but with

    #      slightly different python syntax  for the expressions

    df = pd.DataFrame({

        'x': [0, 1, 2, 3],

        'y': ['zero', 'one', 'two', 'three']})

    df >> define(z='x')

    """

       x      y  z

    0  0   zero  0

    1  1    one  1

    2  2    two  2

    3  3  three  3

    """

    df >> define(z=if_else('x > 1', 1, 0))

    """

       x      y  z

    0  0   zero  0

    1  1    one  0

    2  2    two  1

    3  3  three  1

    """

    # You can pass the dataframe as the # first argument

    query(df, 'x > 1')  # same as `df >> query('x > 1')`

    """

       x      y

    2  2    two

    3  3  three

    """

    # You can use the ply function instead of the >> operator

    ply(df,

        define(z=if_else('x > 1', 1, 0)),

        query('z == 1')

    )

    """

        x      y  z

     2  2    two  1

     3  3  three  1

    """

    # The >>= operator can be used to modify the dataframe

    # if there is a single operation

    df >>= define(two_x='2*x')

    df

    """

        x      y  two_x

     0  0   zero      0

     1  1    one      2

     2  2    two      4

     3  3  three      6

    """

    # df >>= define(two_x='2*x') >> define(three_x='3*x')

    # is two operations and does not work

plydata piping works with `plotnine`_.

.. code-block:: python

    from plotnine import ggplot, aes, geom_line

    df = pd.DataFrame({'x': np.linspace(0, 2*np.pi, 500)})

    (df

     >> define(y='np.sin(x)')

     >> define(sign=if_else('y >= 0', '"positive"', '"negative"'))

     >> (ggplot(aes('x', 'y'))

         + geom_line(aes(color='sign'), size=1.5))

     )

.. figure:: ./doc/images/readme-image.png

What about dplython or pandas-ply?

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

`dplython`_ and `pandas-ply`_ are two other packages that have a similar

objective to plydata. The big difference is plydata does not use

a placeholder variable (`X`) as a stand-in for the dataframe. For example:

.. code-block:: python

    diamonds >> select(X.carat, X.cut, X.price)  # dplython

    diamonds >> select('carat', 'cut', 'price')  # plydata

    select(diamonds, 'carat', 'cut', 'price')    # plydata

For more, see the documentation_.

.. |release| image:: https://img.shields.io/pypi/v/plydata.svg

.. _release: https://pypi.python.org/pypi/plydata

.. |license| image:: https://img.shields.io/pypi/l/plydata.svg

.. _license: https://pypi.python.org/pypi/plydata

.. |buildstatus| image:: https://github.com/has2k1/plydata/workflows/build/badge.svg?branch=master

.. _buildstatus: https://github.com/has2k1/plydata/actions?query=branch%3Amaster+workflow%3A%22build%22

.. |coverage| image:: https://codecov.io /github/has2k1/plydata/coverage.svg?branch=master

.. _coverage: https://codecov.io/github/has2k1/plydata?branch=master

.. |documentation| image:: https://readthedocs.org/projects/plydata/badge/?version=latest

.. _documentation: https://plydata.readthedocs.io/en/latest/

.. |documentation_stable| image:: https://readthedocs.org/projects/plydata/badge/?version=stable

.. _documentation_stable: https://plydata.readthedocs.io/en/stable/

.. _dplyr: https://github.com/tidyverse/dplyr

.. _tidyr: https://github.com/tidyverse/tidyr

.. _forcats: https://github.com/tidyverse/forcats

.. _pandas-ply: https://github.com/coursera/pandas-ply

.. _dplython: https://github.com/dodger487/dplython

.. _plotnine: https://plotnine.readthedocs.io/en/stable/