@Override
public Map<Long, Long> findFS() {
int[] usedCounts = Arrays.copyOfRange(counts, 0, capwidth);
// initial frequency is the same as what we see from counters
Map<Integer, Long> freq =
Arrays.stream(usedCounts)
.boxed()
.collect(Collectors.groupingBy(Integer::intValue, Collectors.counting()));
Long zeroNum = freq.get(0);
if (zeroNum != null && zeroNum == capwidth) {
return new HashMap<>();
}
// estimate the number of items
int num = (int) (capwidth * Math.log(1.0 * capwidth / zeroNum));
Distribution newDistribution = new Distribution(freq);
Distribution oldDistribution = new Distribution();
// A pattern is a setting of itmes+frequencies that sum to sumI
// All patterns in this list will map to a common number sumI
List<Map<Integer, Integer>> patterns = new ArrayList<>();
List<Double> probabilities = new ArrayList<>();
int iterations = 0;
// iteratively update the distribution
// while (notConverged()) {
while (iterations < MAXIMUM_ITERATIONS) {
oldDistribution.fillFrom(newDistribution);
newDistribution.clear();
for (Map.Entry<Integer, Long> entry : freq.entrySet()) {
int sumI = entry.getKey();
int freqI = entry.getValue().intValue();
if (sumI == 0) { // skip key=0
continue;
}
// find new probable patterns, get their probabilities and update the distribution
getPatterns(patterns, sumI, freqI, oldDistribution);
computeProbabilities(patterns, oldDistribution, probabilities);
Iterator<Double> probabilityIterator = probabilities.iterator();
for (Map<Integer, Integer> pattern : patterns) { // for each pattern
double probability = probabilityIterator.next();
for (Map.Entry<Integer, Integer> patternEntry : pattern.entrySet()) {
newDistribution.addFreq(
patternEntry.getKey(), freqI * patternEntry.getValue() * probability);
}
}
}
// scale factor to make sum of distribution equal to 1
double scale = num / newDistribution.sumFreq();
pw.println(
String.format(
DISTRIBUTION_TRACE_FORMATTER,
getStep() + 1,
iterations + 1,
newDistribution.toString(scale)));
iterations++;
}
pw.flush();
System.out.println(getStep());
Map<Long, Long> output = new HashMap<>();
double freqSum = newDistribution.sumFreq();
for (Map.Entry<Integer, Double> entry : newDistribution.freq.entrySet()) {
output.put(entry.getKey().longValue(), (long) (entry.getValue() / freqSum * num));
}
return output;
}
