####### 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/[email protected]

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
"""

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/