de.gwdg.metadataqa.marc.utils.BasicStatistics Maven / Gradle / Ivy

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package de.gwdg.metadataqa.marc.utils;

import org.apache.commons.lang3.StringUtils;

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

public class BasicStatistics {
  private final Map histogram;
  private Integer min = null;
  private Integer max = null;
  private Double mean = null;
  private Double stdDev = null;
  private long count = 0;
  private long sum = 0;

  public BasicStatistics(Map histogram) {
    this.histogram = histogram;
    calculate();
  }

  private void calculate() {
    count = 0;
    sum = 0;
    if (histogram == null || histogram.isEmpty()) {
      mean = 0.0;
      stdDev = 0.0;
      min = 0;
      max = 0;
    } else {
      for (Map.Entry entry : histogram.entrySet()) {
        if (min == null) {
          min = entry.getKey();
        } else {
          min = Math.min(min, entry.getKey());
        }

        if (max == null) {
          max = entry.getKey();
        } else {
          max = Math.max(max, entry.getKey());
        }

        count += entry.getValue();
        sum += entry.getKey() * entry.getValue();
      }
      mean = sum * 1.0 / count;
      calculateStdDevAndMedian();
    }
  }

  private void calculateStdDevAndMedian() {
    double sum = 0.0;
    long aggregatedSum = 0;
    for (Map.Entry entry : histogram.entrySet()) {
      sum += Math.pow(entry.getKey() - mean, 2);
      aggregatedSum += entry.getValue();
      // if ()
    }
    stdDev = Math.sqrt(sum) / count;
  }

  public Integer getMin() {
    return min;
  }

  public Integer getMax() {
    return max;
  }

  public Double getMean() {
    return mean;
  }

  public String formatHistogram() {
    List histogramList = new ArrayList<>();
    if (histogram != null && !histogram.isEmpty()) {
      for (Map.Entry histogram : histogram.entrySet()) {
        histogramList.add(histogram.getKey() + "=" + histogram.getValue());
      }
    }
    return StringUtils.join(histogramList, "; ");
  }

  public Double getStdDev() {
    return stdDev;
  }
}