Change points reported different from MOA - Method _detect_change

[denisesato]

Versions

river version: 0.21.2
Python version: 3.12
Operating system: Windows 11

Describe the bug

Steps/code to reproduce

# Sample code to reproduce the problem
# Please do your best to provide a Minimal, Reproducible Example: https://stackoverflow.com/help/minimal-reproducible-example

from river import drift
import pandas as pd

def read_attribute(complete_filename, attribute):
    print(f'Reading file {complete_filename}...')
    df = pd.read_csv(complete_filename)
    durations = df[attribute].tolist()
    return durations

def analyze_changes(attribute_series, delta):
    detector = drift.ADWIN(delta=delta)
    num_instances = 0
    changes = []
    # normalized_durations = normalize([durations], norm="max")[0].tolist()
    # for d in normalized_durations:
    for value in attribute_series:
        num_instances += 1
        detector.update(value)
        print(f'ADWIN variance ({num_instances}): {detector.variance} - {detector.estimation} - {detector.width}')
        if detector.drift_detected:
            changes.append(num_instances)
            print(
                f'****** Change detected in data: {value} - at instance: {num_instances}')
    print(f'---- Changes detected at: {changes} -----')
    return changes


if __name__ == '__main__':
    complete_filename = 'data/input/ARFFLogArtificial01P300C10A.csv'
    series = read_attribute(complete_filename, 'Duration')
    drifts = analyze_changes(attribute_series=series, delta=0.05)

# Sample code to reproduce in MOA
import com.github.javacliparser.FloatOption;
import moa.classifiers.core.driftdetection.ADWINChangeDetector;
import moa.core.InstanceExample;
import moa.streams.ArffFileStream;

import java.util.ArrayList;
import java.util.List;

public class TestAdwin {

    public static void main(String[] args) {
        String filename = "data/input/ARFFLogArtificial01P300C10A.arff";
        ADWINChangeDetector detector = new ADWINChangeDetector();
        detector.deltaAdwinOption = new FloatOption("deltaAdwin", 'a',
                "Delta of Adwin change detection", 0.05, 0.0, 1.0);

        ArffFileStream reader = new ArffFileStream();
        reader.arffFileOption.setValue(filename);

        // salva as alterações para cada detector
        List<Integer> changes = new ArrayList<Integer>();
        System.out.println("--- Reading: " + filename);
        reader.prepareForUse();
        reader.restart();
        int qtdInstancias = 0;

        detector.prepareForUse();
        detector.resetLearning();

        while (reader.hasMoreInstances()) {
            qtdInstancias++;
            InstanceExample instanceExample = reader.nextInstance();
            double val = instanceExample.getData().value(0);
            detector.input(val);

            System.out.println("ADWIN variance (" + qtdInstancias + "): " + detector.getEstimation());

            // verifica se detectou mudanca
            if (detector.getChange()) {
                System.out.println("--- Change detected at: " + qtdInstancias);
                changes.add(qtdInstancias);
                detector.resetLearning();
            }
        }
        System.out.println("--- Changes at: " + changes);
    }

}

ARFFLogArtificial01P300C10A.csv