A grammar for data manipulation in Python
####### plydata #######
========================= ======================= Latest Release |release|_ License |license|_ Build Status |buildstatus|_ Coverage |coverage|_ Documentation (Dev) |documentation|_ Documentation (Release) |documentationstable| ========================= =======================
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(twox='2x') >> define(threex='3x') # 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 .. documentationstable: 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/
