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Added JavaDeveloperApiExample.java and fixed other issues: Made devel…
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…oper API private[spark] for now. Added constructors Java can understand to specialized Param types.
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jkbradley committed Feb 6, 2015
1 parent 8316d5e commit fec348a
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Original file line number Diff line number Diff line change
Expand Up @@ -121,5 +121,7 @@ public static void main(String[] args) {
System.out.println("(" + r.get(0) + ", " + r.get(1) + ") --> prob=" + r.get(2)
+ ", prediction=" + r.get(3));
}

jsc.stop();
}
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,217 @@
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package org.apache.spark.examples.ml;

import java.util.List;

import com.google.common.collect.Lists;

import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.ml.classification.Classifier;
import org.apache.spark.ml.classification.ClassificationModel;
import org.apache.spark.ml.param.IntParam;
import org.apache.spark.ml.param.ParamMap;
import org.apache.spark.ml.param.Params;
import org.apache.spark.ml.param.Params$;
import org.apache.spark.mllib.linalg.BLAS;
import org.apache.spark.mllib.linalg.Vector;
import org.apache.spark.mllib.linalg.Vectors;
import org.apache.spark.mllib.regression.LabeledPoint;
import org.apache.spark.sql.DataFrame;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.SQLContext;


/**
* A simple example demonstrating how to write your own learning algorithm using Estimator,
* Transformer, and other abstractions.
* This mimics {@link org.apache.spark.ml.classification.LogisticRegression}.
*
* Run with
* <pre>
* bin/run-example ml.JavaDeveloperApiExample
* </pre>
*/
public class JavaDeveloperApiExample {

public static void main(String[] args) throws Exception {
SparkConf conf = new SparkConf().setAppName("JavaDeveloperApiExample");
JavaSparkContext jsc = new JavaSparkContext(conf);
SQLContext jsql = new SQLContext(jsc);

// Prepare training data.
List<LabeledPoint> localTraining = Lists.newArrayList(
new LabeledPoint(1.0, Vectors.dense(0.0, 1.1, 0.1)),
new LabeledPoint(0.0, Vectors.dense(2.0, 1.0, -1.0)),
new LabeledPoint(0.0, Vectors.dense(2.0, 1.3, 1.0)),
new LabeledPoint(1.0, Vectors.dense(0.0, 1.2, -0.5)));
DataFrame training = jsql.applySchema(jsc.parallelize(localTraining), LabeledPoint.class);

// Create a LogisticRegression instance. This instance is an Estimator.
MyJavaLogisticRegression lr = new MyJavaLogisticRegression();
// Print out the parameters, documentation, and any default values.
System.out.println("MyJavaLogisticRegression parameters:\n" + lr.explainParams() + "\n");

// We may set parameters using setter methods.
lr.setMaxIter(10);

// Learn a LogisticRegression model. This uses the parameters stored in lr.
MyJavaLogisticRegressionModel model = lr.fit(training);

// Prepare test data.
List<LabeledPoint> localTest = Lists.newArrayList(
new LabeledPoint(1.0, Vectors.dense(-1.0, 1.5, 1.3)),
new LabeledPoint(0.0, Vectors.dense(3.0, 2.0, -0.1)),
new LabeledPoint(1.0, Vectors.dense(0.0, 2.2, -1.5)));
DataFrame test = jsql.applySchema(jsc.parallelize(localTest), LabeledPoint.class);

// Make predictions on test documents. cvModel uses the best model found (lrModel).
DataFrame results = model.transform(test);
double sumPredictions = 0;
for (Row r : results.select("features", "label", "prediction").collect()) {
sumPredictions += r.getDouble(2);
}
if (sumPredictions != 0.0) {
throw new Exception("MyJavaLogisticRegression predicted something other than 0," +
" even though all weights are 0!");
}

jsc.stop();
}
}

/**
* Example of defining a type of {@link Classifier}.
*
* NOTE: This is private since it is an example. In practice, you may not want it to be private.
*/
class MyJavaLogisticRegression
extends Classifier<Vector, MyJavaLogisticRegression, MyJavaLogisticRegressionModel>
implements Params {

/**
* Param for max number of iterations
* <p/>
* NOTE: The usual way to add a parameter to a model or algorithm is to include:
* - val myParamName: ParamType
* - def getMyParamName
* - def setMyParamName
*/
IntParam maxIter = new IntParam(this, "maxIter", "max number of iterations");

int getMaxIter() { return (int)get(maxIter); }

public MyJavaLogisticRegression() {
setMaxIter(100);
}

// The parameter setter is in this class since it should return type MyJavaLogisticRegression.
MyJavaLogisticRegression setMaxIter(int value) {
return (MyJavaLogisticRegression)set(maxIter, value);
}

// This method is used by fit().
// In Java, we have to make it public since Java does not understand Scala's protected modifier.
public MyJavaLogisticRegressionModel train(DataFrame dataset, ParamMap paramMap) {
// Extract columns from data using helper method.
JavaRDD<LabeledPoint> oldDataset = extractLabeledPoints(dataset, paramMap).toJavaRDD();

// Do learning to estimate the weight vector.
int numFeatures = oldDataset.take(1).get(0).features().size();
Vector weights = Vectors.zeros(numFeatures); // Learning would happen here.

// Create a model, and return it.
return new MyJavaLogisticRegressionModel(this, paramMap, weights);
}
}

/**
* Example of defining a type of {@link ClassificationModel}.
*
* NOTE: This is private since it is an example. In practice, you may not want it to be private.
*/
class MyJavaLogisticRegressionModel
extends ClassificationModel<Vector, MyJavaLogisticRegressionModel> implements Params {

private MyJavaLogisticRegression parent_;
public MyJavaLogisticRegression parent() { return parent_; }

private ParamMap fittingParamMap_;
public ParamMap fittingParamMap() { return fittingParamMap_; }

private Vector weights_;
public Vector weights() { return weights_; }

public MyJavaLogisticRegressionModel(
MyJavaLogisticRegression parent_,
ParamMap fittingParamMap_,
Vector weights_) {
this.parent_ = parent_;
this.fittingParamMap_ = fittingParamMap_;
this.weights_ = weights_;
}

// This uses the default implementation of transform(), which reads column "features" and outputs
// columns "prediction" and "rawPrediction."

// This uses the default implementation of predict(), which chooses the label corresponding to
// the maximum value returned by [[predictRaw()]].

/**
* Raw prediction for each possible label.
* The meaning of a "raw" prediction may vary between algorithms, but it intuitively gives
* a measure of confidence in each possible label (where larger = more confident).
* This internal method is used to implement [[transform()]] and output [[rawPredictionCol]].
*
* @return vector where element i is the raw prediction for label i.
* This raw prediction may be any real number, where a larger value indicates greater
* confidence for that label.
*
* In Java, we have to make this method public since Java does not understand Scala's protected
* modifier.
*/
public Vector predictRaw(Vector features) {
double margin = BLAS.dot(features, weights_);
// There are 2 classes (binary classification), so we return a length-2 vector,
// where index i corresponds to class i (i = 0, 1).
return Vectors.dense(-margin, margin);
}

/**
* Number of classes the label can take. 2 indicates binary classification.
*/
public int numClasses() { return 2; }

/**
* Create a copy of the model.
* The copy is shallow, except for the embedded paramMap, which gets a deep copy.
* <p/>
* This is used for the defaul implementation of [[transform()]].
*
* In Java, we have to make this method public since Java does not understand Scala's protected
* modifier.
*/
public MyJavaLogisticRegressionModel copy() {
MyJavaLogisticRegressionModel m =
new MyJavaLogisticRegressionModel(parent_, fittingParamMap_, weights_);
Params$.MODULE$.inheritValues(this.paramMap(), this, m);
return m;
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -107,5 +107,7 @@ public static void main(String[] args) {
System.out.println("(" + r.get(0) + ", " + r.get(1) + ") -> prob=" + r.get(2)
+ ", prediction=" + r.get(3));
}

jsc.stop();
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -88,5 +88,7 @@ public static void main(String[] args) {
System.out.println("(" + r.get(0) + ", " + r.get(1) + ") --> prob=" + r.get(2)
+ ", prediction=" + r.get(3));
}

jsc.stop();
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -29,9 +29,11 @@ import org.apache.spark.sql.types.{DataType, DoubleType, StructType}
/**
* :: DeveloperApi ::
* Params for classification.
*
* NOTE: This is currently private[spark] but will be made public later once it is stabilized.
*/
@DeveloperApi
trait ClassifierParams extends PredictorParams
private[spark] trait ClassifierParams extends PredictorParams
with HasRawPredictionCol {

override protected def validateAndTransformSchema(
Expand All @@ -53,9 +55,11 @@ trait ClassifierParams extends PredictorParams
* @tparam FeaturesType Type of input features. E.g., [[Vector]]
* @tparam Learner Concrete Estimator type
* @tparam M Concrete Model type
*
* NOTE: This is currently private[spark] but will be made public later once it is stabilized.
*/
@AlphaComponent
abstract class Classifier[
private[spark] abstract class Classifier[
FeaturesType,
Learner <: Classifier[FeaturesType, Learner, M],
M <: ClassificationModel[FeaturesType, M]]
Expand All @@ -75,8 +79,11 @@ abstract class Classifier[
*
* @tparam FeaturesType Type of input features. E.g., [[Vector]]
* @tparam M Concrete Model type
*
* NOTE: This is currently private[spark] but will be made public later once it is stabilized.
*/
@AlphaComponent
private[spark]
abstract class ClassificationModel[FeaturesType, M <: ClassificationModel[FeaturesType, M]]
extends PredictionModel[FeaturesType, M] with ClassifierParams {

Expand Down Expand Up @@ -161,7 +168,7 @@ private[ml] object ClassificationModel {
* should already be done.
* @return (number of columns added, transformed dataset)
*/
private[ml] def transformColumnsImpl[FeaturesType](
def transformColumnsImpl[FeaturesType](
dataset: DataFrame,
model: ClassificationModel[FeaturesType, _],
map: ParamMap): (Int, DataFrame) = {
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,10 @@ package org.apache.spark.ml.classification
import org.apache.spark.annotation.AlphaComponent
import org.apache.spark.ml.param._
import org.apache.spark.mllib.classification.LogisticRegressionWithLBFGS
import org.apache.spark.mllib.linalg.{BLAS, Vector, Vectors}
import org.apache.spark.mllib.linalg.{VectorUDT, BLAS, Vector, Vectors}
import org.apache.spark.sql.DataFrame
import org.apache.spark.sql.Dsl._
import org.apache.spark.sql.types.DoubleType
import org.apache.spark.storage.StorageLevel


Expand Down Expand Up @@ -102,13 +104,82 @@ class LogisticRegressionModel private[ml] (
1.0 / (1.0 + math.exp(-m))
}

override def transform(dataset: DataFrame, paramMap: ParamMap): DataFrame = {
// This is overridden (a) to be more efficient (avoiding re-computing values when creating
// multiple output columns) and (b) to handle threshold, which the abstractions do not use.
// TODO: We should abstract away the steps defined by UDFs below so that the abstractions
// can call whichever UDFs are needed to create the output columns.

// Check schema
transformSchema(dataset.schema, paramMap, logging = true)

val map = this.paramMap ++ paramMap

// Output selected columns only.
// This is a bit complicated since it tries to avoid repeated computation.
// rawPrediction (-margin, margin)
// probability (1.0-score, score)
// prediction (max margin)
var tmpData = dataset
var numColsOutput = 0
if (map(rawPredictionCol) != "") {
val features2raw: Vector => Vector = (features) => predictRaw(features)
tmpData = tmpData.select($"*",
callUDF(features2raw, new VectorUDT, col(map(featuresCol))).as(map(rawPredictionCol)))
numColsOutput += 1
}
if (map(probabilityCol) != "") {
if (map(rawPredictionCol) != "") {
val raw2prob: Vector => Vector = { (rawPreds: Vector) =>
val prob1 = 1.0 / (1.0 + math.exp(-rawPreds(1)))
Vectors.dense(1.0 - prob1, prob1)
}
tmpData = tmpData.select($"*",
callUDF(raw2prob, new VectorUDT, col(map(rawPredictionCol))).as(map(probabilityCol)))
} else {
val features2prob: Vector => Vector = (features: Vector) => predictProbabilities(features)
tmpData = tmpData.select($"*",
callUDF(features2prob, new VectorUDT, col(map(featuresCol))).as(map(probabilityCol)))
}
numColsOutput += 1
}
if (map(predictionCol) != "") {
val t = map(threshold)
if (map(probabilityCol) != "") {
val predict: Vector => Double = { probs: Vector =>
if (probs(1) > t) 1.0 else 0.0
}
tmpData = tmpData.select($"*",
callUDF(predict, DoubleType, col(map(probabilityCol))).as(map(predictionCol)))
} else if (map(rawPredictionCol) != "") {
val predict: Vector => Double = { rawPreds: Vector =>
val prob1 = 1.0 / (1.0 + math.exp(-rawPreds(1)))
if (prob1 > t) 1.0 else 0.0
}
tmpData = tmpData.select($"*",
callUDF(predict, DoubleType, col(map(rawPredictionCol))).as(map(predictionCol)))
} else {
val predict: Vector => Double = (features: Vector) => this.predict(features)
tmpData = tmpData.select($"*",
callUDF(predict, DoubleType, col(map(featuresCol))).as(map(predictionCol)))
}
numColsOutput += 1
}
if (numColsOutput == 0) {
this.logWarning(s"$uid: LogisticRegressionModel.transform() was called as NOOP" +
" since no output columns were set.")
}
tmpData
}

override val numClasses: Int = 2

/**
* Predict label for the given feature vector.
* The behavior of this can be adjusted using [[threshold]].
*/
override protected def predict(features: Vector): Double = {
println(s"LR.predict with threshold: ${paramMap(threshold)}")
if (score(features) > paramMap(threshold)) 1 else 0
}

Expand Down
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