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Scoring H2O MOJO Models With Spark UDF and Scala [Code Snippets]

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Scoring H2O MOJO Models With Spark UDF and Scala [Code Snippets]

The best case scenario when dealing with H2O machine learning is that your machine learning models are able to be exported as Java code. Here's how to do just that!

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With H2O machine learning, the best case is that your machine learning models can be exported as Java code so that you can use them for scoring in any platform that supports Java. H2O algorithms generate POJO and MOJO models, which doesn't require H2O runtime to score which is great for any enterprise. You can learn more about H2O POJO and MOJO models here.

Here is the Spark Scala code, which shows how to score the H2O MOJO model by loading it from the disk and then uses a RowData object to pass as a row to H2O easyPredict class:

import _root_.hex.genmodel.GenModel
import _root_.hex.genmodel.easy.{EasyPredictModelWrapper, RowData}
import _root_.hex.genmodel.easy.prediction
import _root_.hex.genmodel.MojoModel
import _root_.hex.genmodel.easy.RowData

// Load Mojo
val mojo = MojoModel.load("/Users/avkashchauhan/learn/customers/mojo_bin/gbm_model.zip")
val easyModel = new EasyPredictModelWrapper(mojo)

// Get Mojo Details
var features = mojo.getNames.toBuffer

// Creating the row
val r = new RowData
r.put("AGE", "68")
r.put("RACE", "2")
r.put("DCAPS", "2")
r.put("VOL", "0")
r.put("GLEASON", "6")

// Performing the Prediction
val prediction = easyModel.predictBinomial(r).classProbabilities

Above, the MOJO model is stored into local file system as gbm_prostate_model.zip and is loaded as resources inside the Scala code. The full execution of above code is available here.

Following is the simple Java code, which shows how you can use the same code to write a Java application to perform scoring based on an H2O MOJO model:

import java.io.*;
import hex.genmodel.easy.RowData;
import hex.genmodel.easy.EasyPredictModelWrapper;
import hex.genmodel.easy.prediction.*;
import hex.genmodel.MojoModel;
import java.util.Arrays;

public class main {
  public static void main(String[] args) throws Exception {
    EasyPredictModelWrapper model = new EasyPredictModelWrapper(MojoModel.load("gbm_prostate_model.zip"));

    hex.genmodel.GenModel mojo = MojoModel.load("gbm_prostate_model.zip");

    System.out.println("isSupervised : " + mojo.isSupervised());
    System.out.println("Columns Names : " + Arrays.toString(mojo.getNames()));
    System.out.println("Number of columns : " + mojo.getNumCols());
    System.out.println("Response ID : " + mojo.getResponseIdx());
    System.out.println("Response Name : " + mojo.getResponseName());

    for (int i = 0; i < mojo.getNumCols(); i++) {
      String[] domainValues = mojo.getDomainValues(i);

    RowData row = new RowData();
    row.put("AGE", "68");
    row.put("RACE", "2");
    row.put("DCAPS", "2");
    row.put("VOL", "0");
    row.put("GLEASON", "6");

    BinomialModelPrediction p = model.predictBinomial(row);
    System.out.println("Has penetrated the prostatic capsule (1=yes; 0=no): " + p.label);
    System.out.print("Class probabilities: ");
    for (int i = 0; i < p.classProbabilities.length; i++) {
      if (i > 0) {

That's it — enjoy!

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h2o ,machine learning ,scala ,apache spark ,udf ,scoring models ,algorithm ,ai

Published at DZone with permission of Avkash Chauhan, DZone MVB. See the original article here.

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