Package com.googlecode.javaewah32

Class EWAHCompressedBitmap32

  • All Implemented Interfaces:
    LogicalElement<EWAHCompressedBitmap32>, BitmapStorage32, Externalizable, Serializable, Cloneable, Iterable<Integer>
    public final class EWAHCompressedBitmap32
extends Object
implements Cloneable, Externalizable, Iterable<Integer>, BitmapStorage32, LogicalElement<EWAHCompressedBitmap32>

    This implements the patent-free EWAH scheme. Roughly speaking, it is a 32-bit variant of the BBC compression scheme used by Oracle for its bitmap indexes.

    In contrast with the 64-bit EWAH scheme (javaewah.EWAHCompressedBitmap), you can expect this class to compress better, but to be slower at processing the data. In effect, there is a trade-off between memory usage and performances.

    Here is a code sample to illustrate usage:

     EWAHCompressedBitmap32 ewahBitmap1 = EWAHCompressedBitmap32.bitmapOf(0, 2, 55, 64,
         1 << 30);
 EWAHCompressedBitmap32 ewahBitmap2 = EWAHCompressedBitmap32.bitmapOf(1, 3, 64,
         1 << 30);
 EWAHCompressedBitmap32 ewahBitmap3 = EWAHCompressedBitmap32
         .bitmapOf(5, 55, 1 << 30);
 EWAHCompressedBitmap32 ewahBitmap4 = EWAHCompressedBitmap32
         .bitmapOf(4, 66, 1 << 30);
 EWAHCompressedBitmap32 orBitmap = ewahBitmap1.or(ewahBitmap2);
 EWAHCompressedBitmap32 andbitmap = ewahBitmap1.and(ewahBitmap2);
 EWAHCompressedBitmap32 xorbitmap = ewahBitmap1.xor(ewahBitmap2);
 andbitmap = EWAHCompressedBitmap32.and(ewahBitmap1, ewahBitmap2, ewahBitmap3,
         ewahBitmap4);
 ByteArrayOutputStream bos = new ByteArrayOutputStream();
 ObjectOutputStream oo = new ObjectOutputStream(bos);
 ewahBitmap1.writeExternal(oo);
 oo.close();
 ewahBitmap1 = null;
 ewahBitmap1 = new EWAHCompressedBitmap32();
 ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
 ewahBitmap1.readExternal(new ObjectInputStream(bis));
 EWAHCompressedBitmap32 threshold2 = EWAHCompressedBitmap32.threshold(2,
         ewahBitmap1, ewahBitmap2, ewahBitmap3, ewahBitmap4);

    The objective of this compression type is to provide some compression, while reducing as much as possible the CPU cycle usage.

    Once constructed, the bitmap is essentially immutable (unless you call the "set" or "add" methods). Thus, it can be safely used in multi-threaded programs.

    For more details, see the following papers:

    Since:
    0.5.0
    See Also:
    EWAHCompressedBitmap, Serialized Form

    • Field Detail

      • ADJUST_CONTAINER_SIZE_WHEN_AGGREGATING

        public static final boolean ADJUST_CONTAINER_SIZE_WHEN_AGGREGATING
        whether we adjust after some aggregation by adding in zeroes *
        See Also:
        Constant Field Values

      • WORD_IN_BITS

        public static final int WORD_IN_BITS
        The Constant WORD_IN_BITS represents the number of bits in a int.
        See Also:
        Constant Field Values

    • Constructor Detail

      • EWAHCompressedBitmap32

        public EWAHCompressedBitmap32()
        Creates an empty bitmap (no bit set to true).

      • EWAHCompressedBitmap32

        public EWAHCompressedBitmap32​(int bufferSize)
        Sets explicitly the buffer size (in 32-bit words). The initial memory usage will be "bufferSize * 32". For large poorly compressible bitmaps, using large values may improve performance. If the requested bufferSize is less than 1, a value of 1 is used by default. In particular, negative values of bufferSize are effectively ignored.
        Parameters:
        bufferSize - number of 32-bit words reserved when the object is created)

      • EWAHCompressedBitmap32

        public EWAHCompressedBitmap32​(ByteBuffer buffer)
        Creates a bitmap with the specified ByteBuffer backend. It assumes that a bitmap was serialized at this location. It is effectively "deserialized" though the actual content is not copied. This might be useful for implementing memory-mapped bitmaps.
        Parameters:
        buffer - data source

      • EWAHCompressedBitmap32

        public EWAHCompressedBitmap32​(IntBuffer buffer)
        Creates a bitmap with the specified java.nio.IntBuffer backend. The content of the IntBuffer is discarded.
        Parameters:
        buffer - data source

    • Method Detail

      • add

        @Deprecated
public void add​(int newData)
        Deprecated.
        use addWord() instead.
        Parameters:
        newData - the word

      • add

        @Deprecated
public void add​(int newData,
                int bitsThatMatter)
        Deprecated.
        use addWord() instead.
        Parameters:
        newData - the word
        bitsThatMatter - the number of significant bits (by default it should be 64)

      • addWord

        public void addWord​(int newData)
        Adding words directly to the bitmap (for expert use). This method adds bits in words of 4*8 bits. It is not to be confused with the set method which sets individual bits. Most users will want the set method. Example: if you add word 321 to an empty bitmap, you are have added (in binary notation) 0b101000001, so you have effectively called set(0), set(6), set(8) in sequence. Since this modifies the bitmap, this method is not thread-safe. API change: prior to version 0.8.3, this method was called add.
        Specified by:
        addWord in interface BitmapStorage32
        Parameters:
        newData - the word

      • addWord

        public void addWord​(int newData,
                    int bitsThatMatter)
        Adding words directly to the bitmap (for expert use). Since this modifies the bitmap, this method is not thread-safe. API change: prior to version 0.8.3, this method was called add.
        Parameters:
        newData - the word
        bitsThatMatter - the number of significant bits (by default it should be 32)

      • addLiteralWord

        public void addLiteralWord​(int newData)
        Adding literal words directly to the bitmap (for expert use). Since this modifies the bitmap, this method is not thread-safe.
        Specified by:
        addLiteralWord in interface BitmapStorage32
        Parameters:
        newData - the literal word

      • addStreamOfLiteralWords

        public void addStreamOfLiteralWords​(com.googlecode.javaewah32.Buffer32 buffer,
                                    int start,
                                    int number)
        if you have several literal words to copy over, this might be faster. Since this modifies the bitmap, this method is not thread-safe.
        Specified by:
        addStreamOfLiteralWords in interface BitmapStorage32
        Parameters:
        buffer - the buffer wrapping the literal words
        start - the starting point in the array
        number - the number of literal words to add

      • addStreamOfEmptyWords

        public void addStreamOfEmptyWords​(boolean v,
                                  int number)
        For experts: You want to add many zeroes or ones? This is the method you use. Since this modifies the bitmap, this method is not thread-safe.
        Specified by:
        addStreamOfEmptyWords in interface BitmapStorage32
        Parameters:
        v - the boolean value
        number - the number

      • addStreamOfNegatedLiteralWords

        public void addStreamOfNegatedLiteralWords​(com.googlecode.javaewah32.Buffer32 buffer,
                                           int start,
                                           int number)
        Same as addStreamOfLiteralWords, but the words are negated. Since this modifies the bitmap, this method is not thread-safe.
        Specified by:
        addStreamOfNegatedLiteralWords in interface BitmapStorage32
        Parameters:
        buffer - the buffer wrapping the literal words
        start - the starting point in the array
        number - the number of literal words to add

      • and

        public EWAHCompressedBitmap32 and​(EWAHCompressedBitmap32 a)
        Returns a new compressed bitmap containing the bitwise AND values of the current bitmap with some other bitmap. The current bitmap is not modified. The running time is proportional to the sum of the compressed sizes (as reported by sizeInBytes()). If you are not planning on adding to the resulting bitmap, you may call the trim() method to reduce memory usage.
        Specified by:
        and in interface LogicalElement<EWAHCompressedBitmap32>
        Parameters:
        a - the other bitmap (it will not be modified)
        Returns:
        the EWAH compressed bitmap

      • andToContainer

        public void andToContainer​(EWAHCompressedBitmap32 a,
                           BitmapStorage32 container)
        Computes new compressed bitmap containing the bitwise AND values of the current bitmap with some other bitmap. The current bitmap is not modified. The running time is proportional to the sum of the compressed sizes (as reported by sizeInBytes()). The content of the container is overwritten.
        Parameters:
        a - the other bitmap (it will not be modified)
        container - where we store the result
        Since:
        0.4.0

      • andCardinality

        public int andCardinality​(EWAHCompressedBitmap32 a)
        Returns the cardinality of the result of a bitwise AND of the values of the current bitmap with some other bitmap. Avoids allocating an intermediate bitmap to hold the result of the OR. The current bitmap is not modified.
        Parameters:
        a - the other bitmap (it will not be modified)
        Returns:
        the cardinality

      • andNot

        public EWAHCompressedBitmap32 andNot​(EWAHCompressedBitmap32 a)
        Returns a new compressed bitmap containing the bitwise AND NOT values of the current bitmap with some other bitmap. The current bitmap is not modified. The running time is proportional to the sum of the compressed sizes (as reported by sizeInBytes()). If you are not planning on adding to the resulting bitmap, you may call the trim() method to reduce memory usage.
        Specified by:
        andNot in interface LogicalElement<EWAHCompressedBitmap32>
        Parameters:
        a - the other bitmap (it will not be modified)
        Returns:
        the EWAH compressed bitmap

      • andNotToContainer

        public void andNotToContainer​(EWAHCompressedBitmap32 a,
                              BitmapStorage32 container)
        Returns a new compressed bitmap containing the bitwise AND NOT values of the current bitmap with some other bitmap. The current bitmap is not modified. The running time is proportional to the sum of the compressed sizes (as reported by sizeInBytes()). The content of the container is overwritten.
        Parameters:
        a - the other bitmap (it will not be modified)
        container - where we store the result

      • andNotCardinality

        public int andNotCardinality​(EWAHCompressedBitmap32 a)
        Returns the cardinality of the result of a bitwise AND NOT of the values of the current bitmap with some other bitmap. Avoids allocating an intermediate bitmap to hold the result of the OR. The current bitmap is not modified.
        Parameters:
        a - the other bitmap (it will not be modified)
        Returns:
        the cardinality

      • cardinality

        public int cardinality()
        reports the number of bits set to true. Running time is proportional to compressed size (as reported by sizeInBytes).
        Returns:
        the number of bits set to true

      • clear

        public void clear()
        Clear any set bits and set size in bits back to 0
        Specified by:
        clear in interface BitmapStorage32

      • serialize

        public void serialize​(DataOutput out)
               throws IOException
        Serialize. The current bitmap is not modified.
        Parameters:
        out - the DataOutput stream
        Throws:
        IOException - Signals that an I/O exception has occurred.

      • deserialize

        public void deserialize​(DataInput in)
                 throws IOException
        Deserialize.
        Parameters:
        in - the ObjectInput stream
        Throws:
        IOException - Signals that an I/O exception has occurred.

      • getEWAHIterator

        public EWAHIterator32 getEWAHIterator()
        Gets an EWAHIterator32 over the data. This is a customized iterator which iterates over run length words. For experts only. The current bitmap is not modified.
        Returns:
        the EWAHIterator32

      • getIteratingRLW

        public IteratingRLW32 getIteratingRLW()
        Gets an IteratingRLW to iterate over the data. For experts only. Note that iterator does not know about the size in bits of the bitmap: the size in bits is effectively rounded up to the nearest multiple of 32. However, if you materialize a bitmap from an iterator, you can set the desired size in bits using the setSizeInBitsWithinLastWord methods: EWAHCompressedBitmap32 n = IteratorUtil32.materialize(bitmap.getIteratingRLW())); n.setSizeInBitsWithinLastWord(bitmap.sizeInBits()); The current bitmap is not modified.
        Returns:
        the IteratingRLW iterator corresponding to this bitmap

      • getPositions

        @Deprecated
public List<Integer> getPositions()
        Deprecated.
        use toList() instead.
        Returns:
        a list

      • toList

        public List<Integer> toList()
        Gets the locations of the true values as one list. (May use more memory than iterator().) The current bitmap is not modified. API change: prior to version 0.8.3, this method was called getPositions.
        Returns:
        the positions

      • hashCode

        public int hashCode()
        Returns a customized hash code (based on Karp-Rabin). Naturally, if the bitmaps are equal, they will hash to the same value. The current bitmap is not modified.
        Overrides:
        hashCode in class Object

      • intersects

        public boolean intersects​(EWAHCompressedBitmap32 a)
        Return true if the two EWAHCompressedBitmap have both at least one true bit in the same position. Equivalently, you could call "and" and check whether there is a set bit, but intersects will run faster if you don't need the result of the "and" operation. The current bitmap is not modified.
        Parameters:
        a - the other bitmap (it will not be modified)
        Returns:
        whether they intersect

      • intIterator

        public IntIterator intIterator()
        Iterator over the set bits (this is what most people will want to use to browse the content if they want an iterator). The location of the set bits is returned, in increasing order. The current bitmap is not modified.
        Returns:
        the int iterator

      • reverseIntIterator

        public IntIterator reverseIntIterator()
        Iterator over the set bits in reverse order. The current bitmap is not modified.
        Returns:
        the int iterator

      • isEmpty

        public boolean isEmpty()
        Checks whether this bitmap is empty (has a cardinality of zero).
        Returns:
        true if no bit is set

      • clearIntIterator

        public IntIterator clearIntIterator()
        Iterator over the clear bits. The location of the clear bits is returned, in increasing order. The current bitmap is not modified.
        Returns:
        the int iterator

      • chunkIterator

        public ChunkIterator chunkIterator()
        Iterator over the chunk of bits. The current bitmap is not modified.
        Returns:
        the chunk iterator

      • iterator

        public Iterator<Integer> iterator()
        Iterates over the positions of the true values. This is similar to intIterator(), but it uses Java generics. The current bitmap is not modified.
        Specified by:
        iterator in interface Iterable<Integer>
        Returns:
        the iterator

      • not

        public void not()
        Negate (bitwise) the current bitmap. To get a negated copy, do EWAHCompressedBitmap x= ((EWAHCompressedBitmap) mybitmap.clone()); x.not(); The running time is proportional to the compressed size (as reported by sizeInBytes()). Because this method modifies the bitmap, it is not thread-safe.
        Specified by:
        not in interface LogicalElement<EWAHCompressedBitmap32>

      • or

        public EWAHCompressedBitmap32 or​(EWAHCompressedBitmap32 a)
        Returns a new compressed bitmap containing the bitwise OR values of the current bitmap with some other bitmap. The running time is proportional to the sum of the compressed sizes (as reported by sizeInBytes()). If you are not planning on adding to the resulting bitmap, you may call the trim() method to reduce memory usage. The current bitmap is not modified.
        Specified by:
        or in interface LogicalElement<EWAHCompressedBitmap32>
        Parameters:
        a - the other bitmap (it will not be modified)
        Returns:
        the EWAH compressed bitmap

      • orToContainer

        public void orToContainer​(EWAHCompressedBitmap32 a,
                          BitmapStorage32 container)
        Computes the bitwise or between the current bitmap and the bitmap "a". Stores the result in the container. The current bitmap is not modified. The content of the container is overwritten.
        Parameters:
        a - the other bitmap (it will not be modified)
        container - where we store the result

      • orCardinality

        public int orCardinality​(EWAHCompressedBitmap32 a)
        Returns the cardinality of the result of a bitwise OR of the values of the current bitmap with some other bitmap. Avoids allocating an intermediate bitmap to hold the result of the OR. The current bitmap is not modified.
        Parameters:
        a - the other bitmap (it will not be modified)
        Returns:
        the cardinality

      • serializedSizeInBytes

        public int serializedSizeInBytes()
        Report the number of bytes required to serialize this bitmap. The current bitmap is not modified.
        Returns:
        the size in bytes

      • get

        public boolean get​(int i)
        Query the value of a single bit. Relying on this method when speed is needed is discouraged. The complexity is linear with the size of the bitmap. (This implementation is based on zhenjl's Go version of JavaEWAH.) The current bitmap is not modified.
        Parameters:
        i - the bit we are interested in
        Returns:
        whether the bit is set to true

      • getFirstSetBit

        public int getFirstSetBit()
        getFirstSetBit is a light-weight method that returns the location of the set bit (=1) or -1 if there is none.
        Returns:
        location of the first set bit or -1

      • clear

        public boolean clear​(int i)
        Set the bit at position i to false. Though you can clear the bits in any order (e.g., clear(100), clear(10), clear(1), you will typically get better performance if you clear the bits in increasing order (e.g., clear(1), clear(10), clear(100)). Clearing a bit that is larger than the biggest bit is a constant time operation. Clearing a bit that is smaller than the biggest bit can require time proportional to the compressed size of the bitmap, as the bitmap may need to be rewritten. Since this modifies the bitmap, this method is not thread-safe.
        Parameters:
        i - the index
        Returns:
        true if the value was unset
        Throws:
        IndexOutOfBoundsException - if i is negative or greater than Integer.MAX_VALUE - 32

      • set

        public boolean set​(int i)
        Set the bit at position i to true. Though you can set the bits in any order (e.g., set(100), set(10), set(1), you will typically get better performance if you set the bits in increasing order (e.g., set(1), set(10), set(100)). Setting a bit that is larger than any of the current set bit is a constant time operation. Setting a bit that is smaller than an already set bit can require time proportional to the compressed size of the bitmap, as the bitmap may need to be rewritten. Since this modifies the bitmap, this method is not thread-safe.
        Parameters:
        i - the index
        Returns:
        true if the value was set
        Throws:
        IndexOutOfBoundsException - if i is negative or greater than Integer.MAX_VALUE - 32

      • setSizeInBitsWithinLastWord

        public void setSizeInBitsWithinLastWord​(int size)
        Set the size in bits. This does not change the compressed bitmap.
        Specified by:
        setSizeInBitsWithinLastWord in interface BitmapStorage32
        Parameters:
        size - the size in bits

      • setSizeInBits

        public boolean setSizeInBits​(int size,
                             boolean defaultValue)
        Change the reported size in bits of the *uncompressed* bitmap represented by this compressed bitmap. It may change the underlying compressed bitmap. It is not possible to reduce the sizeInBits, but it can be extended. The new bits are set to false or true depending on the value of defaultValue. This method is not thread-safe.
        Parameters:
        size - the size in bits
        defaultValue - the default boolean value
        Returns:
        true if the update was possible

      • sizeInBits

        public int sizeInBits()
        Returns the size in bits of the *uncompressed* bitmap represented by this compressed bitmap. Initially, the sizeInBits is zero. It is extended automatically when you set bits to true. The current bitmap is not modified.
        Specified by:
        sizeInBits in interface LogicalElement<EWAHCompressedBitmap32>
        Returns:
        the size in bits

      • sizeInBytes

        public int sizeInBytes()
        Report the *compressed* size of the bitmap (equivalent to memory usage, after accounting for some overhead).
        Specified by:
        sizeInBytes in interface LogicalElement<EWAHCompressedBitmap32>
        Returns:
        the size in bytes

      • threshold

        public static EWAHCompressedBitmap32 threshold​(int t,
                                               EWAHCompressedBitmap32... bitmaps)
        Compute a Boolean threshold function: bits are true where at least T bitmaps have a true bit.
        Parameters:
        t - the threshold
        bitmaps - input data
        Returns:
        the aggregated bitmap
        Since:
        0.8.2

      • thresholdWithContainer

        public static void thresholdWithContainer​(BitmapStorage32 container,
                                          int t,
                                          EWAHCompressedBitmap32... bitmaps)
        Compute a Boolean threshold function: bits are true where at least T bitmaps have a true bit. The content of the container is overwritten.
        Parameters:
        t - the threshold
        bitmaps - input data
        container - where we write the aggregated bitmap
        Since:
        0.8.2

      • toArray

        public int[] toArray()
        Populate an array of (sorted integers) corresponding to the location of the set bits.
        Returns:
        the array containing the location of the set bits

      • toDebugString

        public String toDebugString()
        A more detailed string describing the bitmap (useful for debugging).
        Returns:
        the string

      • toString

        public String toString()
        A string describing the bitmap.
        Overrides:
        toString in class Object
        Returns:
        the string

      • swap

        public void swap​(EWAHCompressedBitmap32 other)
        swap the content of the bitmap with another.
        Parameters:
        other - bitmap to swap with

      • trim

        public void trim()
        Reduce the internal buffer to its minimal allowable size (given by this.actualsizeinwords). This can free memory.

      • xor

        public EWAHCompressedBitmap32 xor​(EWAHCompressedBitmap32 a)
        Returns a new compressed bitmap containing the bitwise XOR values of the current bitmap with some other bitmap. The running time is proportional to the sum of the compressed sizes (as reported by sizeInBytes()). If you are not planning on adding to the resulting bitmap, you may call the trim() method to reduce memory usage. The current bitmap is not modified.
        Specified by:
        xor in interface LogicalElement<EWAHCompressedBitmap32>
        Parameters:
        a - the other bitmap (it will not be modified)
        Returns:
        the EWAH compressed bitmap

      • xorToContainer

        public void xorToContainer​(EWAHCompressedBitmap32 a,
                           BitmapStorage32 container)
        Computes a new compressed bitmap containing the bitwise XOR values of the current bitmap with some other bitmap. The running time is proportional to the sum of the compressed sizes (as reported by sizeInBytes()). The current bitmap is not modified. The content of the container is overwritten.
        Parameters:
        a - the other bitmap (it will not be modified)
        container - where we store the result

      • xorCardinality

        public int xorCardinality​(EWAHCompressedBitmap32 a)
        Returns the cardinality of the result of a bitwise XOR of the values of the current bitmap with some other bitmap. Avoids allocating an intermediate bitmap to hold the result of the OR. The current bitmap is not modified.
        Parameters:
        a - the other bitmap (it will not be modified)
        Returns:
        the cardinality

      • compose

        public EWAHCompressedBitmap32 compose​(EWAHCompressedBitmap32 a)
        Returns a new compressed bitmap containing the composition of the current bitmap with some other bitmap. The composition A.compose(B) is defined as follows: we retain the ith set bit of A only if the ith bit of B is set. For example, if you have the following bitmap A = { 0, 1, 0, 1, 1, 0 } and want to keep only the second and third ones, you can call A.compose(B) with B = { 0, 1, 1 } and you will get C = { 0, 0, 0, 1, 1, 0 }. If you are not planning on adding to the resulting bitmap, you may call the trim() method to reduce memory usage. The current bitmap is not modified.
        Specified by:
        compose in interface LogicalElement<EWAHCompressedBitmap32>
        Parameters:
        a - the other bitmap (it will not be modified)
        Returns:
        the EWAH compressed bitmap

      • composeToContainer

        public void composeToContainer​(EWAHCompressedBitmap32 a,
                               EWAHCompressedBitmap32 container)
        Computes a new compressed bitmap containing the composition of the current bitmap with some other bitmap. The composition A.compose(B) is defined as follows: we retain the ith set bit of A only if the ith bit of B is set. For example, if you have the following bitmap A = { 0, 1, 0, 1, 1, 0 } and want to keep only the second and third ones, you can call A.compose(B) with B = { 0, 1, 1 } and you will get C = { 0, 0, 0, 1, 1, 0 }. The current bitmap is not modified. The content of the container is overwritten.
        Parameters:
        a - the other bitmap (it will not be modified)
        container - where we store the result

      • andWithContainer

        public static void andWithContainer​(BitmapStorage32 container,
                                    EWAHCompressedBitmap32... bitmaps)
        For internal use. Computes the bitwise and of the provided bitmaps and stores the result in the container. The content of the container is overwritten.
        Parameters:
        container - where the result is stored
        bitmaps - bitmaps to AND

      • and

        public static EWAHCompressedBitmap32 and​(EWAHCompressedBitmap32... bitmaps)
        Returns a new compressed bitmap containing the bitwise AND values of the provided bitmaps. It may or may not be faster than doing the aggregation two-by-two (A.and(B).and(C)). If only one bitmap is provided, it is returned as is. If you are not planning on adding to the resulting bitmap, you may call the trim() method to reduce memory usage.
        Parameters:
        bitmaps - bitmaps to AND together
        Returns:
        result of the AND

      • andCardinality

        public static int andCardinality​(EWAHCompressedBitmap32... bitmaps)
        Returns the cardinality of the result of a bitwise AND of the values of the provided bitmaps. Avoids allocating an intermediate bitmap to hold the result of the AND.
        Parameters:
        bitmaps - bitmaps to AND
        Returns:
        the cardinality

      • bitmapOf

        public static EWAHCompressedBitmap32 bitmapOf​(int... setbits)
        Return a bitmap with the bit set to true at the given positions. The positions should be given in sorted order. (This is a convenience method.)
        Parameters:
        setbits - list of set bit positions
        Returns:
        the bitmap
        Since:
        0.4.5

      • orWithContainer

        public static void orWithContainer​(BitmapStorage32 container,
                                   EWAHCompressedBitmap32... bitmaps)
        For internal use. Computes the bitwise or of the provided bitmaps and stores the result in the container. The content of the container is overwritten.
        Parameters:
        container - where store the result
        bitmaps - to be aggregated

      • xorWithContainer

        public static void xorWithContainer​(BitmapStorage32 container,
                                    EWAHCompressedBitmap32... bitmaps)
        For internal use. Computes the bitwise xor of the provided bitmaps and stores the result in the container. The content of the container is overwritten.
        Parameters:
        container - where store the result
        bitmaps - to be aggregated

      • or

        public static EWAHCompressedBitmap32 or​(EWAHCompressedBitmap32... bitmaps)
        Returns a new compressed bitmap containing the bitwise OR values of the provided bitmaps. This is typically faster than doing the aggregation two-by-two (A.or(B).or(C).or(D)). If only one bitmap is provided, it is returned as is. If you are not planning on adding to the resulting bitmap, you may call the trim() method to reduce memory usage.
        Parameters:
        bitmaps - bitmaps to OR together
        Returns:
        result of the OR

      • xor

        public static EWAHCompressedBitmap32 xor​(EWAHCompressedBitmap32... bitmaps)
        Returns a new compressed bitmap containing the bitwise XOR values of the provided bitmaps. This is typically faster than doing the aggregation two-by-two (A.xor(B).xor(C).xor(D)). If only one bitmap is provided, it is returned as is. If you are not planning on adding to the resulting bitmap, you may call the trim() method to reduce memory usage.
        Parameters:
        bitmaps - bitmaps to XOR together
        Returns:
        result of the XOR

      • orCardinality

        public static int orCardinality​(EWAHCompressedBitmap32... bitmaps)
        Returns the cardinality of the result of a bitwise OR of the values of the provided bitmaps. Avoids allocating an intermediate bitmap to hold the result of the OR.
        Parameters:
        bitmaps - bitmaps to OR
        Returns:
        the cardinality

      • shift

        public EWAHCompressedBitmap32 shift​(int b)
        Generates a new bitmap shifted by "b" bits. If b is positive, the position of all set bits is increased by b. The negative case is not supported.
        Parameters:
        b - number of bits
        Returns:
        new shifted bitmap