A grammar for data manipulation in Python
BSD-3-CLAUSE License
####### 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.
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
.. 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
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/