Package it.unimi.dsi.fastutil.ints

Class IntOpenHashBigSet

  • All Implemented Interfaces:
    Hash, IntCollection, IntIterable, IntSet, Size64, Serializable, Cloneable, Iterable<Integer>, Collection<Integer>, Set<Integer>
    public class IntOpenHashBigSet
extends AbstractIntSet
implements Serializable, Cloneable, Hash, Size64
    A type-specific hash big set with with a fast, small-footprint implementation.

    Instances of this class use a hash table to represent a big set: the number of elements in the set is limited only by the amount of core memory. The table (backed by a big array) is filled up to a specified load factor, and then doubled in size to accommodate new entries. If the table is emptied below one fourth of the load factor, it is halved in size; however, the table is never reduced to a size smaller than that at creation time: this approach makes it possible to create sets with a large capacity in which insertions and deletions do not cause immediately rehashing. Moreover, halving is not performed when deleting entries from an iterator, as it would interfere with the iteration process.

    Note that clear() does not modify the hash table size. Rather, a family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class.

    The methods of this class are about 30% slower than those of the corresponding non-big set.

    See Also:
    Hash, HashCommon, Serialized Form

    • Constructor Detail

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(long expected,
                         float f)
        Creates a new hash big set.

        The actual table size will be the least power of two greater than expected/f.

        Parameters:
        expected - the expected number of elements in the set.
        f - the load factor.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(long expected)
        Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor.
        Parameters:
        expected - the expected number of elements in the hash big set.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(Collection<? extends Integer> c,
                         float f)
        Creates a new hash big set copying a given collection.
        Parameters:
        c - a Collection to be copied into the new hash big set.
        f - the load factor.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(IntCollection c,
                         float f)
        Creates a new hash big set copying a given type-specific collection.
        Parameters:
        c - a type-specific collection to be copied into the new hash big set.
        f - the load factor.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(IntCollection c)
        Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.
        Parameters:
        c - a type-specific collection to be copied into the new hash big set.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(IntIterator i,
                         float f)
        Creates a new hash big set using elements provided by a type-specific iterator.
        Parameters:
        i - a type-specific iterator whose elements will fill the new hash big set.
        f - the load factor.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(IntIterator i)
        Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.
        Parameters:
        i - a type-specific iterator whose elements will fill the new hash big set.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(Iterator<?> i,
                         float f)
        Creates a new hash big set using elements provided by an iterator.
        Parameters:
        i - an iterator whose elements will fill the new hash big set.
        f - the load factor.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(Iterator<?> i)
        Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by an iterator.
        Parameters:
        i - an iterator whose elements will fill the new hash big set.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(int[] a,
                         int offset,
                         int length,
                         float f)
        Creates a new hash big set and fills it with the elements of a given array.
        Parameters:
        a - an array whose elements will be used to fill the new hash big set.
        offset - the first element to use.
        length - the number of elements to use.
        f - the load factor.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(int[] a,
                         int offset,
                         int length)
        Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.
        Parameters:
        a - an array whose elements will be used to fill the new hash big set.
        offset - the first element to use.
        length - the number of elements to use.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(int[] a,
                         float f)
        Creates a new hash big set copying the elements of an array.
        Parameters:
        a - an array to be copied into the new hash big set.
        f - the load factor.

      • IntOpenHashBigSet

        public IntOpenHashBigSet​(int[] a)
        Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
        Parameters:
        a - an array to be copied into the new hash big set.

    • Method Detail

      • remove

        public boolean remove​(int k)
        Description copied from class: AbstractIntSet
        Removes an element from this set.

        Note that the corresponding method of a type-specific collection is rem(). This unfortunate situation is caused by the clash with the similarly named index-based method in the List interface. Delegates to the type-specific rem() method implemented by type-specific abstract Collection superclass.

        Specified by:
        remove in interface IntSet
        Overrides:
        remove in class AbstractIntSet
        See Also:
        Collection.remove(Object)

      • trim

        public boolean trim()
        Rehashes this set, making the table as small as possible.

        This method rehashes the table to the smallest size satisfying the load factor. It can be used when the set will not be changed anymore, so to optimize access speed and size.

        If the table size is already the minimum possible, this method does nothing.

        Returns:
        true if there was enough memory to trim the set.
        See Also:
        trim(long)

      • trim

        public boolean trim​(long n)
        Rehashes this set if the table is too large.

        Let N be the smallest table size that can hold max(n,size64()) entries, still satisfying the load factor. If the current table size is smaller than or equal to N, this method does nothing. Otherwise, it rehashes this set in a table of size N.

        This method is useful when reusing sets. Clearing a set leaves the table size untouched. If you are reusing a set many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient sets.

        Parameters:
        n - the threshold for the trimming.
        Returns:
        true if there was enough memory to trim the set.
        See Also:
        trim()

      • size64

        public long size64()
        Description copied from interface: Size64
        Returns the size of this data structure as a long.
        Specified by:
        size64 in interface Size64
        Returns:
        the size of this data structure.

      • clone

        public IntOpenHashBigSet clone()
        Returns a deep copy of this big set.

        This method performs a deep copy of this big hash set; the data stored in the set, however, is not cloned. Note that this makes a difference only for object keys.

        Returns:
        a deep copy of this big set.

      • hashCode

        public int hashCode()
        Returns a hash code for this set. This method overrides the generic method provided by the superclass. Since equals() is not overriden, it is important that the value returned by this method is the same value as the one returned by the overriden method.
        Specified by:
        hashCode in interface Collection<Integer>
        Specified by:
        hashCode in interface Set<Integer>
        Overrides:
        hashCode in class AbstractIntSet
        Returns:
        a hash code for this set.