quarks.analytics.sensors

Class Filters

java.lang.Object

quarks.analytics.sensors.Filters

public class Filters
extends java.lang.Object

Filters aimed at sensors.

Method Summary

Modifier and Type	Method and Description
static <T,V> TStream<T>	deadband(TStream<T> stream, Function<T,V> value, Predicate<V> inBand, long maximumSuppression, java.util.concurrent.TimeUnit unit) Deadband filter with maximum suppression time.
static <T,V> TStream<T>	deadband(TStream<T> stream, Function<T,V> value, Predicate<V> inBand) Deadband filter.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

deadband

public static <T,V> TStream<T> deadband(TStream<T> stream,
                                        Function<T,V> value,
                                        Predicate<V> inBand,
                                        long maximumSuppression,
                                        java.util.concurrent.TimeUnit unit)

Deadband filter with maximum suppression time. A filter that discards any tuples that are in the deadband, uninteresting to downstream consumers.

A tuple t is passed through the deadband filter if:

• inBand.test(value.apply(t)) is false, that is the tuple's value is outside of the deadband
• OR inBand.test(value.apply(t)) is true AND the last tuple's value was outside of the deadband. This corresponds to the first tuple's value inside the deadband after a period being outside it.
• OR it has been more than maximumSuppression seconds (in unit unit)
• OR it is the first tuple (effectively the state of the filter starts as outside of the deadband).

Type Parameters:

T - Tuple type.

V - Value type for the deadband function.

Parameters:

stream - Stream containing readings.

value - Function to obtain the tuple's value passed to the deadband function.

inBand - Function that defines the deadband.

maximumSuppression - Maximum amount of time to suppress values that are in the deadband.

unit - Unit for maximumSuppression.

Returns:

Filtered stream.

deadband

public static <T,V> TStream<T> deadband(TStream<T> stream,
                                        Function<T,V> value,
                                        Predicate<V> inBand)

Deadband filter. A filter that discards any tuples that are in the deadband, uninteresting to downstream consumers.

A tuple t is passed through the deadband filter if:

• inBand.test(value.apply(t)) is false, that is the value is outside of the deadband
• OR inBand.test(value.apply(t)) is true and the last value was outside of the deadband. This corresponds to the first value inside the deadband after a period being outside it.
• OR it is the first tuple (effectively the state of the filter starts as outside of the deadband).

Here's an example of how deadband() would pass through tuples for a sequence of values against the shaded dead band area. Circled values are ones that are passed through the filter to the returned stream.

• All tuples with a value outside the dead band.
• Two tuples with values within the dead band that are the first time values return to being in band after being outside of the dead band.
• The first tuple.

Type Parameters:

T - Tuple type.

V - Value type for the deadband function.

Parameters:

stream - Stream containing readings.

value - Function to obtain the value passed to the deadband function.

inBand - Function that defines the deadband.

Returns:

Filtered stream.