Package ubic.gemma.core.util

Class ListUtils

java.lang.Object

ubic.gemma.core.util.ListUtils

public class ListUtils
extends Object

Utilities and algorithms for List.

Author:

poirigui

Constructor Summary

Constructors

Constructor	Description
ListUtils()

Method Summary

Modifier and Type	Method	Description
static <T> List<List<T>>	batch(List<T> list, int batchSize)
static <T> T	getSparseArrayElement(List<T> array, int[] indices, int numberOfElements, int index, T defaultValue)	Get an element of a sparse array.
static <T> T	getSparseRangeArrayElement(List<T> array, int[] offsets, int numberOfElements, int index)	Get an element of a sparse range array.
static Map<String,Integer>	indexOfCaseInsensitiveStringElements(List<String> list)	Get a case-insensitive mapping of string elements to their first occurrence in a List.
static <T> Map<T,Integer>	indexOfElements(List<T> list)	Get a mapping of element to their first occurrence in a List.
static <T> List<T>	pad(List<T> list, T elementForPadding, int size)	Pad a collection with the given element.
static <T> List<T>	padToNextPowerOfTwo(List<T> list, T elementForPadding)	Pad a collection to the next power of 2 with the given element.
static <T> void	validateSparseArray(List<T> array, int[] indices, int numberOfElements, T defaultValue)
static void	validateSparseRangeArray(List<?> array, int[] offsets, int numberOfElements)	Validate a sparse range array.

Methods inherited from class java.lang.Object

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

Constructor Detail

ListUtils

public ListUtils()

Method Detail

indexOfElements

public static <T> Map<T,Integer> indexOfElements(List<T> list)

Get a mapping of element to their first occurrence in a List.

This of this as an efficient way of calling List.indexOf(Object) in a loop, since it will reduce the complexity to O(n) instead of O(n^2).

I couldn't find this algorithm in Guava nor Apache Collections, but if you do, let me know!

indexOfCaseInsensitiveStringElements

public static Map<String,Integer> indexOfCaseInsensitiveStringElements(List<String> list)

Get a case-insensitive mapping of string elements to their first occurrence in a List.

See Also:

indexOfElements(List)

getSparseArrayElement

public static <T> T getSparseArrayElement(List<T> array,
                                          int[] indices,
                                          int numberOfElements,
                                          int index,
                                          T defaultValue)

Get an element of a sparse array.

validateSparseArray

public static <T> void validateSparseArray(List<T> array,
                                           int[] indices,
                                           int numberOfElements,
                                           @Nullable
                                           T defaultValue)

getSparseRangeArrayElement

public static <T> T getSparseRangeArrayElement(List<T> array,
                                               int[] offsets,
                                               int numberOfElements,
                                               int index)
                                        throws IllegalArgumentException,
                                               IndexOutOfBoundsException

Get an element of a sparse range array.

Parameters:

array - collection of elements applying for the ranges

offsets - starting offsets of the ranges

numberOfElements - the size of the original array

index - a position to retrieve

Throws:

IndexOutOfBoundsException - if the requested index is out of bounds

IllegalArgumentException - if the array is empty or its size differs from offsets

See Also:

validateSparseRangeArray(List, int[], int)

validateSparseRangeArray

public static void validateSparseRangeArray(List<?> array,
                                            int[] offsets,
                                            int numberOfElements)
                                     throws IllegalArgumentException

Validate a sparse range array.

Parameters:

array - collection of elements applying for the ranges

offsets - starting offsets of the ranges

numberOfElements - the size of the original array

Throws:

IllegalArgumentException - if the sparse range array is invalid

padToNextPowerOfTwo

public static <T> List<T> padToNextPowerOfTwo(List<T> list,
                                              T elementForPadding)

Pad a collection to the next power of 2 with the given element.

pad

public static <T> List<T> pad(List<T> list,
                              T elementForPadding,
                              int size)

Pad a collection with the given element.

batch

public static <T> List<List<T>> batch(List<T> list,
                                      int batchSize)