org.semanticweb.elk.util.collections
Class Operations

java.lang.Object
  org.semanticweb.elk.util.collections.Operations

public class Operations
extends Object

Some useful static methods for collections

Author:

"Yevgeny Kazakov"

Nested Class Summary

static interface	Operations.Condition<T> Boolean conditions over some type.
static interface	Operations.Functor<I,O> A simple object that transforms objects of type I to objects of type O
static interface	Operations.FunctorEx<I,O> An extension of Operations.Functor which can do the reverse transformation
static interface	Operations.Transformation<I,O> Transformations of input values to output values

Field Summary

static Multimap<?,?>

EMPTY_MULTIMAP

Constructor Summary

Operations()

Method Summary

static <T> Iterable<T>	concat(Iterable<? extends Iterable<? extends T>> input) Concatenates several Iterables into one
static <T> Iterable<T>	concat(Iterable<? extends T> a, Iterable<? extends T> b)
static <T> void	dumpDiff(Collection<T> first, Collection<T> second, Writer writer, String prefix) Prints the elements present in the first Collection but not in the second Collection using the given Writer and prefixing all messages with a given prefix.
static <K,V> void	dumpDiff(Multimap<K,V> first, Multimap<K,V> second, Writer writer, String prefix) Prints key-value entries present in the first Multimap but not in the second Multimap using the given Writer and prefixing all messages with a given prefix.
static <S,T> Multimap<S,T>	emptyMultimap()
static <T,S> Iterable<T>	filter(Iterable<S> input, Class<T> type)
static <T> Iterable<T>	filter(Iterable<T> input, Operations.Condition<? super T> condition)
static <T> Set<T>	filter(Set<T> input, Operations.Condition<? super T> condition, int size) Returns read-only view of the given set consisting of the elements satisfying a given condition, if the number of such elements is known
static <T> Collection<T>	getCollection(Iterable<T> iterable, int size)
static <I,O> Iterable<O>	map(Iterable<I> input, Operations.Transformation<? super I,O> transformation) Transforms elements using a given Operations.Transformation the output elements consist of the result of the transformation in the same order; if the transformation returns null, it is not included in the output
static <I,O> Set<O>	map(Set<? extends I> input, Operations.FunctorEx<I,O> functor) A simple second-order map function
static <T> Iterable<T>	singleton(T element)
static <T> Collection<ArrayList<T>>	split(Collection<? extends T> elements, int batchSize) Splits the input Collection on batches with at most given number of elements.
static <T> Iterable<ArrayList<T>>	split(Iterable<? extends T> elements, int batchSize) Splits the input Iterable on batches with at most given number of elements.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_MULTIMAP

public static final Multimap<?,?> EMPTY_MULTIMAP

Constructor Detail

Operations

public Operations()

Method Detail

emptyMultimap

public static <S,T> Multimap<S,T> emptyMultimap()

concat

public static <T> Iterable<T> concat(Iterable<? extends T> a,
                                     Iterable<? extends T> b)

singleton

public static <T> Iterable<T> singleton(T element)

concat

public static <T> Iterable<T> concat(Iterable<? extends Iterable<? extends T>> input)

Concatenates several Iterables into one

Parameters:

input - the Iterable of Iterables to be concatenated

Returns:

Iterable consisting of all elements found in input Iterables

split

public static <T> Iterable<ArrayList<T>> split(Iterable<? extends T> elements,
                                               int batchSize)

Splits the input Iterable on batches with at most given number of elements.

Parameters:

elements - the Iterable to be split

batchSize - the maximal number of elements in batches

Returns:

a Iterable of batches containing elements from the input collection

See Also:

concat(Iterable)

split

public static <T> Collection<ArrayList<T>> split(Collection<? extends T> elements,
                                                 int batchSize)

Splits the input Collection on batches with at most given number of elements.

Parameters:

elements - the Collection to be split

batchSize - the maximal number of elements in batches

Returns:

a Collection of batches containing elements from the input collection

getCollection

public static <T> Collection<T> getCollection(Iterable<T> iterable,
                                              int size)

filter

public static <T> Iterable<T> filter(Iterable<T> input,
                                     Operations.Condition<? super T> condition)

Parameters:

input - the input iterator

condition - the condition used for filtering

Returns:

the filtered iterator

filter

public static <T,S> Iterable<T> filter(Iterable<S> input,
                                       Class<T> type)

filter

public static <T> Set<T> filter(Set<T> input,
                                Operations.Condition<? super T> condition,
                                int size)

Returns read-only view of the given set consisting of the elements satisfying a given condition, if the number of such elements is known

Parameters:

input - the given set to be filtered

condition - the condition used for filtering the set. Must be consistent with equals() for T, that is: a.equals(b) must imply that holds(a) == holds(b)

size - the number of elements in the filtered set

Returns:

the set consisting of the elements of the input set satisfying the given condition

map

public static <I,O> Iterable<O> map(Iterable<I> input,
                                    Operations.Transformation<? super I,O> transformation)

Transforms elements using a given Operations.Transformation the output elements consist of the result of the transformation in the same order; if the transformation returns null, it is not included in the output

Parameters:

input - the input elements

transformation - the transformation for elements

Returns:

the transformed output elements

dumpDiff

public static <K,V> void dumpDiff(Multimap<K,V> first,
                                  Multimap<K,V> second,
                                  Writer writer,
                                  String prefix)
                     throws IOException

Prints key-value entries present in the first Multimap but not in the second Multimap using the given Writer and prefixing all messages with a given prefix.

Parameters:

first -

second -

writer -

prefix -

Throws:

IOException

dumpDiff

public static <T> void dumpDiff(Collection<T> first,
                                Collection<T> second,
                                Writer writer,
                                String prefix)
                     throws IOException

Prints the elements present in the first Collection but not in the second Collection using the given Writer and prefixing all messages with a given prefix.

Parameters:

first -

second -

writer -

prefix -

Throws:

IOException

map

public static <I,O> Set<O> map(Set<? extends I> input,
                               Operations.FunctorEx<I,O> functor)

A simple second-order map function

Parameters:

input -

functor -

Returns:

a set which contains the results of applying the functor to the elements in the input set