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median persistence extension
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Signed-off-by: Mark Herwege <[email protected]>
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@mherwege
mherwege committed Aug 12, 2024
1 parent 5eedd27 commit 1864709
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Showing 3 changed files with 484 additions and 5 deletions.
219 changes: 214 additions & 5 deletions ...sistence/src/main/java/org/openhab/core/persistence/extensions/PersistenceExtensions.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1520,11 +1520,6 @@ private static void internalPersist(Item item, TimeSeries timeSeries, @Nullable
if (effectiveServiceId == null) {
return null;
}
Iterable<HistoricItem> result = getAllStatesBetweenWithBoundaries(item, begin, end, effectiveServiceId);
if (result == null) {
return null;
}
Iterator<HistoricItem> it = result.iterator();
ZonedDateTime now = ZonedDateTime.now();
ZonedDateTime beginTime = begin == null ? now : begin;
ZonedDateTime endTime = end == null ? now : end;
Expand All @@ -1534,6 +1529,12 @@ private static void internalPersist(Item item, TimeSeries timeSeries, @Nullable
return historicItem != null ? historicItem.getState() : null;
}

Iterable<HistoricItem> result = getAllStatesBetweenWithBoundaries(item, begin, end, effectiveServiceId);
if (result == null) {
return null;
}
Iterator<HistoricItem> it = result.iterator();

BigDecimal sum = BigDecimal.ZERO;

HistoricItem lastItem = null;
Expand Down Expand Up @@ -1578,6 +1579,214 @@ private static void internalPersist(Item item, TimeSeries timeSeries, @Nullable
return null;
}

/**
* Gets the median value of the state of a given {@link Item} since a certain point in time.
* The default {@link PersistenceService} is used.
*
* @param item the {@link Item} to get the median value for
* @param timestamp the point in time from which to search for the median value
* @return the median value since <code>timestamp</code> or <code>null</code> if no
* previous states could be found or if the default persistence service does not refer to an available
* {@link QueryablePersistenceService}. The current state is included in the calculation.
*/
public static @Nullable State medianSince(Item item, ZonedDateTime timestamp) {
return internalMedianBetween(item, timestamp, null, null);
}

/**
* Gets the median value of the state of a given {@link Item} until a certain point in time.
* The default {@link PersistenceService} is used.
*
* @param item the {@link Item} to get the median value for
* @param timestamp the point in time to which to search for the median value
* @return the median value until <code>timestamp</code> or <code>null</code> if no
* future states could be found or if the default persistence service does not refer to an available
* {@link QueryablePersistenceService}. The current state is included in the calculation.
*/
public static @Nullable State medianUntil(Item item, ZonedDateTime timestamp) {
return internalMedianBetween(item, null, timestamp, null);
}

/**
* Gets the median value of the state of a given {@link Item} between two certain points in time.
* The default {@link PersistenceService} is used.
*
* @param item the {@link Item} to get the median value for
* @param begin the point in time from which to start the summation
* @param end the point in time to which to start the summation
* @return the median value between <code>begin</code> and <code>end</code> or <code>null</code> if no
* states could be found or if the default persistence service does not refer to an available
* {@link QueryablePersistenceService}.
*/
public static @Nullable State medianBetween(Item item, ZonedDateTime begin, ZonedDateTime end) {
return internalMedianBetween(item, begin, end, null);
}

/**
* Gets the median value of the state of a given {@link Item} since a certain point in time.
* The {@link PersistenceService} identified by the <code>serviceId</code> is used.
*
* @param item the {@link Item} to get the median value for
* @param timestamp the point in time from which to search for the median value
* @param serviceId the name of the {@link PersistenceService} to use
* @return the median value since <code>timestamp</code>, or <code>null</code> if no
* previous states could be found or if the persistence service given by <code>serviceId</code> does not
* refer to an available {@link QueryablePersistenceService}. The current state is included in the
* calculation.
*/
public static @Nullable State medianSince(Item item, ZonedDateTime timestamp, @Nullable String serviceId) {
return internalMedianBetween(item, timestamp, null, serviceId);
}

/**
* Gets the median value of the state of a given {@link Item} until a certain point in time.
* The {@link PersistenceService} identified by the <code>serviceId</code> is used.
*
* @param item the {@link Item} to get the median value for
* @param timestamp the point in time to which to search for the median value
* @param serviceId the name of the {@link PersistenceService} to use
* @return the median value until <code>timestamp</code>, or <code>null</code> if no
* future states could be found or if the persistence service given by <code>serviceId</code> does not
* refer to an available {@link QueryablePersistenceService}. The current state is included in the
* calculation.
*/
public static @Nullable State medianUntil(Item item, ZonedDateTime timestamp, @Nullable String serviceId) {
return internalMedianBetween(item, null, timestamp, serviceId);
}

/**
* Gets the median value of the state of a given {@link Item} between two certain points in time.
* The {@link PersistenceService} identified by the <code>serviceId</code> is used.
*
* @param item the {@link Item} to get the median value for
* @param begin the point in time from which to start the summation
* @param end the point in time to which to start the summation
* @param serviceId the name of the {@link PersistenceService} to use
* @return the median value between <code>begin</code> and <code>end</code>, or <code>null</code> if no
* states could be found or if the persistence service given by <code>serviceId</code> does not
* refer to an available {@link QueryablePersistenceService}
*/
public static @Nullable State medianBetween(Item item, ZonedDateTime begin, ZonedDateTime end,
@Nullable String serviceId) {
return internalMedianBetween(item, begin, end, serviceId);
}

private static @Nullable State internalMedianBetween(Item item, @Nullable ZonedDateTime begin,
@Nullable ZonedDateTime end, @Nullable String serviceId) {
String effectiveServiceId = serviceId == null ? getDefaultServiceId() : serviceId;
if (effectiveServiceId == null) {
return null;
}
ZonedDateTime now = ZonedDateTime.now();
ZonedDateTime beginTime = begin == null ? now : begin;
ZonedDateTime endTime = end == null ? now : end;

if (beginTime.isEqual(endTime)) {
HistoricItem historicItem = internalPersistedState(item, beginTime, effectiveServiceId);
return historicItem != null ? historicItem.getState() : null;
}

Iterable<HistoricItem> result = getAllStatesBetween(item, beginTime, endTime, effectiveServiceId);
if (result == null) {
return null;
}

Item baseItem = item;
if (baseItem instanceof GroupItem groupItem) {
baseItem = groupItem.getBaseItem();
}
Unit<?> unit = baseItem instanceof NumberItem numberItem ? numberItem.getUnit() : null;

ArrayList<BigDecimal> resultList = new ArrayList<>();
result.forEach(hi -> {
DecimalType dtState = getPersistedValue(hi, unit);
if (dtState != null) {
resultList.add(dtState.toBigDecimal());
}
});

int size = resultList.size();
if (size >= 0) {
int k = size / 2;
BigDecimal median = QuickSelect.quickSelect(resultList, k);
if (size % 2 == 0) {
BigDecimal median2 = QuickSelect.quickSelect(resultList, k - 1);
if ((median != null) && (median2 != null)) {
median = median.add(median2).divide(new BigDecimal(2));
}
}

if (median != null) {
if (unit != null) {
return new QuantityType<>(median, unit);
} else {
return new DecimalType(median);
}
}
}
return null;
}

/**
* Class implementing the quickSelect algorithm.
* See https://en.wikipedia.org/wiki/Quickselect and https://gist.github.com/unnikked/14c19ba13f6a4bfd00a3
*/
private static class QuickSelect {
/**
* Find the k-smallest element in a list.
*
* @param bdList, list elements will be reordered in place
* @param k
* @return
*/
static @Nullable BigDecimal quickSelect(ArrayList<BigDecimal> bdList, int k) {
int left = 0;
int right = bdList.size() - 1;
if (right < 0) {
return null;
} else if (right == 0) {
return bdList.get(right);
}

for (;;) {
int pivotIndex = randomPivot(left, right);
pivotIndex = partition(bdList, left, right, pivotIndex);

if (k == pivotIndex) {
return bdList.get(k);
} else if (k < pivotIndex) {
right = pivotIndex - 1;
} else {
left = pivotIndex + 1;
}
}
}

private static int partition(ArrayList<BigDecimal> bdList, int left, int right, int pivotIndex) {
BigDecimal pivotValue = bdList.get(pivotIndex);
swap(bdList, pivotIndex, right); // move pivot to end
int storeIndex = left;
for (int i = left; i < right; i++) {
if (bdList.get(i).compareTo(pivotValue) < 0) {
swap(bdList, storeIndex, i);
storeIndex++;
}
}
swap(bdList, right, storeIndex); // Move pivot to its final place
return storeIndex;
}

private static void swap(ArrayList<BigDecimal> bdList, int a, int b) {
BigDecimal tmp = bdList.get(a);
bdList.set(a, bdList.get(b));
bdList.set(b, tmp);
}

private static int randomPivot(int left, int right) {
return left + (int) Math.floor(Math.random() * (right - left + 1));
}
}

/**
* Gets the sum of the state of a given <code>item</code> since a certain point in time.
* The default persistence service is used.
Expand Down
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