SkLearn2PMML-Plugin

The simplest way to extend SkLearn2PMML package with custom transformation and model types.

Features

A template project with the following layout:

• src/main/python - Base directory for Python classes.
• src/main/java - Base directory for the corresponding Java classes.
• src/main/resources/META-INF/sklearn2pmml.properties - The mappings from Python classes to Java classes.

Example transformer classes:

• com.mycompany.Aggregator. Implements "min", "max" and "mean" aggregation functionality in agreement with PMML built-in functions "min", "max" and "avg", respectively.
• com.mycompany.PowerFunction. Implements power function in agreement with the PMML built-in function "pow".
• com.mycompany.StringNormalizer - Implements string normalization (conversion to lower/uppercase followed by trimming whitespace) in agreement with PMML built-in functions "uppercase", "lowercase" and "trimBlanks".

Prerequisites

• Python 2.7, 3.4 or newer.
• Java 1.7 or newer.

Installation

Enter the project root directory and build using Apache Maven:

mvn clean install

The build produces an EGG file target/sklearn2pmml_plugin-1.0rc0.egg and a JAR file target/sklearn2pmml-plugin-1.0-SNAPSHOT.jar.

Usage

Add the EGG file to the PYTHONPATH environment variable:

export PYTHONPATH=$PYTHONPATH:/path/to/sklearn2pmml-plugin/target/sklearn2pmml_plugin-1.0rc0.egg

Fit an example pipeline:

import pandas

iris_df = pandas.read_csv("Iris.csv")

from sklearn2pmml import PMMLPipeline
from sklearn2pmml.decoration import ContinuousDomain
from sklearn_pandas import DataFrameMapper
from sklearn.linear_model import LogisticRegression
from com.mycompany import Aggregator, PowerFunction

iris_pipeline = PMMLPipeline([
	("mapper", DataFrameMapper([
		(["Sepal.Length", "Petal.Length"], [ContinuousDomain(), Aggregator(function = "mean")]),
		(["Sepal.Width", "Petal.Width"], [ContinuousDomain(), PowerFunction(power = 2)])
	])),
	("classifier", LogisticRegression())
])
iris_pipeline.fit(iris_df, iris_df["Species"])

Export the example pipeline to a PMML file. Use the user_classpath argument to specify the location of the JAR file:

from sklearn2pmml import sklearn2pmml

sklearn2pmml(iris_pipeline, "Iris.pmml", user_classpath = ["/path/to/sklearn2pmml-plugin/target/sklearn2pmml-plugin-1.0-SNAPSHOT.jar"])

The PMML representation of transformers varies depending on the "composition" of the pipeline. In the example example, the com.mycompany.Aggregator transformer is represented as a DerivedField element, whereas the com.mycompany.PowerFunction transformer is represented as a NumericPredictor@exponent attribute:

<PMML xmlns="http://www.dmg.org/PMML-4_3" version="4.3">
	<TransformationDictionary>
		<DerivedField name="avg(Sepal.Length, Petal.Length)" optype="continuous" dataType="double">
			<Apply function="avg">
				<FieldRef field="Sepal.Length"/>
				<FieldRef field="Petal.Length"/>
			</Apply>
		</DerivedField>
	</TransformationDictionary>
	<RegressionModel functionName="classification" normalizationMethod="softmax">
		<MiningSchema>
			<MiningField name="Species" usageType="target"/>
			<MiningField name="Sepal.Width"/>
			<MiningField name="Petal.Width"/>
			<MiningField name="Sepal.Length"/>
			<MiningField name="Petal.Length"/>
		</MiningSchema>
		<RegressionTable intercept="0.15312185052146582" targetCategory="setosa">
			<NumericPredictor name="avg(Sepal.Length, Petal.Length)" coefficient="-1.5862823598313542"/>
			<NumericPredictor name="Sepal.Width" exponent="2" coefficient="0.864623482260917"/>
			<NumericPredictor name="Petal.Width" exponent="2" coefficient="-1.7337433442275574"/>
		</RegressionTable>
		<RegressionTable intercept="-0.41196434155188394" targetCategory="versicolor">
			<NumericPredictor name="avg(Sepal.Length, Petal.Length)" coefficient="1.6174796043315152"/>
			<NumericPredictor name="Sepal.Width" exponent="2" coefficient="-0.5854978099617918"/>
			<NumericPredictor name="Petal.Width" exponent="2" coefficient="-1.4870454407048939"/>
		</RegressionTable>
		<RegressionTable intercept="-1.0913325888211003" targetCategory="virginica">
			<NumericPredictor name="avg(Sepal.Length, Petal.Length)" coefficient="-0.3554755078012205"/>
			<NumericPredictor name="Sepal.Width" exponent="2" coefficient="-0.569705884824069"/>
			<NumericPredictor name="Petal.Width" exponent="2" coefficient="2.9003699714343223"/>
		</RegressionTable>
	</RegressionModel>
</PMML>

License

SkLearn2PMML-Plugin is licensed under the GNU Affero General Public License (AGPL) version 3.0. Other licenses are available on request.

Additional information

Please contact [email protected]