Evaluate a Decision Tree with Lookup

This example combines the evaluation of a decision tree with lookup functionality, offering you a powerful tool for data processing and decision-making. By incorporating lookup capabilities, you can retrieve additional information or make data-driven decisions based on external data sources, enhancing the decision-making process within the evaluation of the decision tree.

Decision Tree is a hierarchical structure that represents a series of conditions and outcomes. It is used to evaluate input data by following the branches of the tree, checking conditions at each node, and ultimately reaching a final outcome based on the satisfied conditions.


Java Code Listing

package com.northconcepts.datapipeline.foundations.examples.decisiontree;

import com.northconcepts.datapipeline.core.FieldList;
import com.northconcepts.datapipeline.core.Record;
import com.northconcepts.datapipeline.foundations.decisiontree.DecisionTree;
import com.northconcepts.datapipeline.foundations.decisiontree.DecisionTreeNode;
import com.northconcepts.datapipeline.foundations.decisiontree.DecisionTreeResult;
import com.northconcepts.datapipeline.internal.expression.DefaultExpressionContext;
import com.northconcepts.datapipeline.transform.lookup.BasicLookup;
import com.northconcepts.datapipeline.transform.lookup.Lookup;

public class EvaluateADecisionTreeWithLookup {

    public static void main(String[] args) {
        DefaultExpressionContext input = new DefaultExpressionContext();
        input.setValue("Price", 159);
        input.setValue("Currency Code", "cad");

        Lookup currencyLookup = new BasicLookup(new FieldList("Currency Name"))
            .add("CAD", "Canadian Dollars")
            .add("USD", "American Dollars")
            .add("EUR", "Euros")
            .add("GBP", "British Pounds")
            .add("MXN", "Mexican Pesos");

        DecisionTree tree = new DecisionTree()

            .setValue("currencyLookup", currencyLookup)
            .setRootNode(new DecisionTreeNode()
                .addNode(new DecisionTreeNode("Price == null || Price < 20")
                    .addOutcome("Shipping", "0.00")
                    .addOutcome("Currency", "lookup(0, currencyLookup, toUpperCase(${Currency Code}))"))
                .addNode(new DecisionTreeNode("Price  < 50")
                    .addOutcome("Shipping", "5.00")
                    .addOutcome("Currency", "lookup(0, currencyLookup, toUpperCase(${Currency Code}))"))
                .addNode(new DecisionTreeNode("Price  < 100")
                    .addOutcome("Shipping", "7.00")
                    .addOutcome("Currency", "lookup(0, currencyLookup, toUpperCase(${Currency Code}))"))
                .addNode(new DecisionTreeNode("Price  >= 100")
                    .addOutcome("Shipping", "${Price} * 0.10")
                    .addOutcome("Currency", "lookup(0, currencyLookup, toUpperCase(${Currency Code}))")));

        DecisionTreeResult result = tree.evaluate(input);
        Record outcome = result.getOutcome();

        System.out.println("outcome = " + outcome);


Code Walkthrough

  1. DefaultExpressionContext is defined as the input of the decision tree where we set properties such as PriceCurrency Code.
  2. BasicLookup is created to specify additional information about Currency. A new field Currency Name is added with five rows.
  3. Then, a DecisionTree is initialized and currencyLookup specified in the previous step is applied.
  4. A root node and a variety of child nodes having conditions on properties are then added.
  5. In order to attach an outcome with a node, addOutcome() method is invoked.
  6. The input is then evaluated and stored in a DecisionTreeResult instance.
  7. Finally, getOutcome() is invoked to display the results of the evaluation on the console.


Console Output

outcome = Record (MODIFIED) {
    1:[Currency]:STRING=[Canadian Dollars]:String
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