Package org.apache.datasketches.tuple.arrayofdoubles

Class ArrayOfDoublesSketch

java.lang.Object
org.apache.datasketches.tuple.arrayofdoubles.ArrayOfDoublesSketch
Direct Known Subclasses:
ArrayOfDoublesCompactSketch, ArrayOfDoublesUpdatableSketch
public abstract class ArrayOfDoublesSketch
extends Object
The base class for the tuple sketch of type ArrayOfDoubles, where an array of double values is associated with each key. A primitive array of doubles is used here, as opposed to a generic Summary object, for improved performance.

  • Method Details

    • heapify

      public static ArrayOfDoublesSketch heapify​(org.apache.datasketches.memory.Memory mem)
      Heapify the given Memory as an ArrayOfDoublesSketch
      Parameters:
      mem - the given Memory
      Returns:
      an ArrayOfDoublesSketch

    • heapify

      public static ArrayOfDoublesSketch heapify​(org.apache.datasketches.memory.Memory mem, long seed)
      Heapify the given Memory and seed as a ArrayOfDoublesSketch
      Parameters:
      mem - the given Memory
      seed - the given seed
      Returns:
      an ArrayOfDoublesSketch

    • wrap

      public static ArrayOfDoublesSketch wrap​(org.apache.datasketches.memory.Memory mem)
      Wrap the given Memory as an ArrayOfDoublesSketch
      Parameters:
      mem - the given Memory
      Returns:
      an ArrayOfDoublesSketch

    • wrap

      public static ArrayOfDoublesSketch wrap​(org.apache.datasketches.memory.Memory mem, long seed)
      Wrap the given Memory and seed as a ArrayOfDoublesSketch
      Parameters:
      mem - the given Memory
      seed - the given seed
      Returns:
      an ArrayOfDoublesSketch

    • getEstimate

      public double getEstimate()
      Estimates the cardinality of the set (number of unique values presented to the sketch)
      Returns:
      best estimate of the number of unique values

    • getUpperBound

      public double getUpperBound​(int numStdDev)
      Gets the approximate upper error bound given the specified number of Standard Deviations. This will return getEstimate() if isEmpty() is true.
      Parameters:
      numStdDev - See Number of Standard Deviations
      Returns:
      the upper bound.

    • getLowerBound

      public double getLowerBound​(int numStdDev)
      Gets the approximate lower error bound given the specified number of Standard Deviations. This will return getEstimate() if isEmpty() is true.
      Parameters:
      numStdDev - See Number of Standard Deviations
      Returns:
      the lower bound.

    • isEmpty

      public boolean isEmpty()
      See Empty
      Returns:
      true if empty.

    • getNumValues

      public int getNumValues()
      Returns:
      number of double values associated with each key

    • isEstimationMode

      public boolean isEstimationMode()
      Returns true if the sketch is Estimation Mode (as opposed to Exact Mode). This is true if theta < 1.0 AND isEmpty() is false.
      Returns:
      true if the sketch is in estimation mode.

    • getTheta

      public double getTheta()
      Gets the value of theta as a double between zero and one
      Returns:
      the value of theta as a double

    • getRetainedEntries

      public abstract int getRetainedEntries()
      Returns:
      number of retained entries

    • toByteArray

      public abstract byte[] toByteArray()
      Returns:
      serialized representation of the sketch

    • getValues

      public abstract double[][] getValues()
      Returns:
      array of arrays of double values in the sketch

    • iterator

      public abstract ArrayOfDoublesSketchIterator iterator()
      Returns:
      iterator over the sketch

    • toString

      public String toString()
      Overrides:
      toString in class Object