de.javagl.sampling.list

Class ListSplitting

java.lang.Object

de.javagl.sampling.list.ListSplitting

public class ListSplitting
extends Object

Methods to split lists. The methods provide views on "chunks" of other lists, or views that omit chunks of other lists.

Method Summary

Modifier and Type	Method and Description
static <T> List<T>	extractChunk(List<? extends T> list, int numChunks, int chunkIndex) Virtually splits the given list into the given number of chunks, and returns an unmodifiable view on the chunk with the given index.
static <T> Stream<List<T>>	extractChunks(List<T> list, int numChunks) Creates a stream that provides the given number of chunks from the given list, in form of unmodifiable lists.
static <T> List<T>	omitChunk(List<? extends T> list, int numChunks, int chunkIndex) Virtually splits the given list into the given number of chunks, and returns an unmodifiable view on the list, omitting the chunk with the given index.
static <T> Stream<List<T>>	omitChunks(List<T> list, int numChunks) Creates a stream that provides lists where chunks of the given list are omitted, in form of unmodifiable lists.

Methods inherited from class java.lang.Object

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

Method Detail

extractChunks

public static <T> Stream<List<T>> extractChunks(List<T> list,
                                                int numChunks)

Creates a stream that provides the given number of chunks from the given list, in form of unmodifiable lists.

The stream will attempt to divide the given list into equal-sized chunks. If the size of the list is not divisible by the given number of chunks, then the last chunks will contain one fewer element than the first ones.

For example, a call with

 list = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
 numChunks = 3
 

will create a stream that contains lists

 [ 0, 1, 2, 3 ]
 [ 4, 5, 6 ]
 [ 7, 8, 9 ]
 

(This means that if the number of chunks is greater than the size of the list, then the last chunks will be empty lists).

If the given list is modified after this stream has been created, the behavior of the stream is unspecified.

If the given list is modified after the chunks have been obtained from the stream, the behavior of the chunks is unspecified.

Type Parameters:

T - The element type

Parameters:

list - The input list

numChunks - The number of chunks

Returns:

The resulting lists

Throws:

IllegalArgumentException - If the number of chunks is smaller than 1

omitChunks

public static <T> Stream<List<T>> omitChunks(List<T> list,
                                             int numChunks)

Creates a stream that provides lists where chunks of the given list are omitted, in form of unmodifiable lists.

The stream will attempt to divide the given list into equal-sized chunks. If the size of the list is not divisible by the given number of chunks, then the last chunks will contain one fewer element than the first ones.

For example, a call with

 list = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
 numChunks = 3
 

will create a stream that returns lists

 [ _  _  _  _  4, 5, 6, 7, 8, 9 ]
 [ 0, 1, 2, 3, _  _  _  7, 8, 9 ]
 [ 0, 1, 2, 3, 4, 5, 6  _  _  _ ]
 

(This means that if the number of chunks is greater than the size of the list, then the last elements will be the whole input list!).

If the given list is modified after this stream has been created, the behavior of the stream is unspecified.

If the given list is modified after the chunks have been obtained from the stream, the behavior of the chunks is unspecified.

Type Parameters:

T - The element type

Parameters:

list - The input list

numChunks - The number of chunks

Returns:

The resulting lists

Throws:

IllegalArgumentException - If the number of chunks is smaller than 1

extractChunk

public static <T> List<T> extractChunk(List<? extends T> list,
                                       int numChunks,
                                       int chunkIndex)

Virtually splits the given list into the given number of chunks, and returns an unmodifiable view on the chunk with the given index.

Type Parameters:

T - The type of the elements

Parameters:

list - the backing list

numChunks - The number of chunks

chunkIndex - The index of the chunk to return

Returns:

The view on the chunk

Throws:

IllegalArgumentException - If the number of chunks is smaller than 1, or the chunk index is negative or not smaller than the number of chunks

omitChunk

public static <T> List<T> omitChunk(List<? extends T> list,
                                    int numChunks,
                                    int chunkIndex)

Virtually splits the given list into the given number of chunks, and returns an unmodifiable view on the list, omitting the chunk with the given index.

Type Parameters:

T - The type of the elements

Parameters:

list - the backing list

numChunks - The number of chunks

chunkIndex - The index of the chunk to return

Returns:

The view on the list, except for the specified chunk

Throws:

IllegalArgumentException - If the number of chunks is smaller than 1, or the chunk index is negative or not smaller than the number of chunks