ak0da/main.go

package main

import (
	"fmt"
	"log"
	"os"

	"github.com/sjwhitworth/golearn/base"
	"github.com/sjwhitworth/golearn/trees"
)

var (
	fname          = "data.csv"
	outliers       = 15
	randomDataSize = 10001
)

func main() {
	data, err := loadData()
	if err != nil {
		log.Fatalln(err)
	}

	log.Printf(
		"Train Isolation Forest model (nTrees: %d, maxDepth: %d, subSpace: %d) on the data\n",
		1000, 1000, 7500,
	)

	predictions := train(data)

	log.Println("Calculate avg/min scores")

	avg := 0.0
	minScore := 1.0

	for i := 0; i < randomDataSize; i++ {
		tmp := predictions[i]

		avg += tmp

		if tmp < minScore {
			minScore = tmp
		}
	}

	fmt.Fprintf(os.Stderr, "\tAverage anomaly score for normal data: %f\n",
		avg/float64(randomDataSize),
	)
	fmt.Fprintf(os.Stderr, "\tMinimum anomaly score for normal data: %f\n",
		minScore,
	)

	// these values should be much higher as comapred to the scores for normal
	// data.
	fmt.Fprintln(os.Stderr, "\tAnomaly scores for outliers are:")

	for i := randomDataSize; i < (randomDataSize + outliers); i++ {
		fmt.Fprint(os.Stderr, "\t")
		fmt.Fprintln(os.Stderr, predictions[i])
	}

	log.Println("we're done")
}

func train(data *base.DenseInstances) []float64 {
	// get a new Isolation Forest with 700 trees, max depth 700 and each tree
	// using 7500 datapoints.
	forest := trees.NewIsolationForest(1000, 1000, 7500)

	// fit the isolation forest to the data.
	forest.Fit(data)

	// return predictions.
	return forest.Predict(data)
}

func loadData() (*base.DenseInstances, error) {
	// generate and save random data, along with known outlier values.
	err := prepData(fname)
	if err != nil {
		return nil, err
	}

	data, err := base.ParseCSVToInstances(fname, false)
	if err != nil {
		return nil, err
	}

	return data, nil
}