Scoring H2O MOJO models with spark UDF and Scala

With H2O machine learning the best case is that your machine learning models can be exported as Java code so you can use them for scoring in any platform which supports Java. H2O algorithms generates POJO and MOJO models which does not 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 using RowData object to pass as 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 it 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 could use the same code to write a Java application to perform scoring based on 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);
      System.out.println(Arrays.toString(domainValues));
    }

    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) {
    System.out.print(",");
      }
      System.out.print(p.classProbabilities[i]);
    }
    System.out.println("");
  }
}

Thats it, enjoy!!

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Calculating Standard Deviation using custom UDF and group by in H2O

Here is the full code to calculate standard deviation using H2O group by method as well as using customer UDF:

library(h2o)
h2o.init()
irisPath <- system.file("extdata", "iris_wheader.csv", package = "h2o")
iris.hex <- h2o.uploadFile(path = irisPath, destination_frame = "iris.hex")

# Calculating Standard Deviation using h2o group by
SdValue <- h2o.group_by(data = iris.hex, by = "class", sd("sepal_len"))

# Printing result
SdValue

# Alternative defining a UDF for Standard Deviation
mySDUdf <- function(df) { sd(df[,1],na.rm = T) }

# Using h2o ddply with UDF
SdValue <- h2o.ddply(iris.hex, "class", mySDUdf)

# Printing result
SdValue

Thats it, enjoy!!

Calculate mean using UDF in H2O

Here is the full code to write a UDF to calculate mean for a given data frame using H2O machine learning platform:

 

library(h2o)
h2o.init()
ausPath <- system.file("extdata", "australia.csv", package="h2o")
australia.hex <- h2o.uploadFile(path = ausPath)

# Writing the UDF
myMeanUDF = function(Fr) { mean(Fr[, 1]) }

# Applying UDF using ddply
MeanValue = h2o.ddply(australia.hex[, c("premax", "salmax", "Max_czcs")], c("premax", "salmax"), myMeanUDF)

# Printing Results
MeanValue

Thats it, enjoy!!