public class ObjectSorting extends PersistentObject
This is another case demonstrating one primary goal of this library: Delivering easy to use, yet very efficient APIs. The sorts return convenient sort views. This enables the usage of algorithms which scale well with the problem size: For example, sorting a 1000000 x 10000 or a 1000000 x 100 x 100 matrix performs just as fast as sorting a 1000000 x 1 matrix. This is so, because internally the algorithms only move around integer indexes, they do not physically move around entire rows or slices. The original matrix is left unaffected.
The quicksort is a derivative of the JDK 1.2 V1.26 algorithms (which are, in turn, based on Bentley's and McIlroy's fine work). The mergesort is a derivative of the JAL algorithms, with optimisations taken from the JDK algorithms. Mergesort is stable (by definition), while quicksort is not. A stable sort is, for example, helpful, if matrices are sorted successively by multiple columns. It preserves the relative position of equal elements.
GenericSorting,
Sorting,
Arrays,
Serialized Form| Modifier and Type | Field and Description |
|---|---|
static ObjectSorting |
mergeSort
A prefabricated mergesort.
|
static ObjectSorting |
quickSort
A prefabricated quicksort.
|
| Modifier and Type | Method and Description |
|---|---|
ObjectMatrix1D |
sort(ObjectMatrix1D vector)
Sorts the vector into ascending order, according to the natural
ordering.
|
ObjectMatrix1D |
sort(ObjectMatrix1D vector,
Comparator c)
Sorts the vector into ascending order, according to the order induced by
the specified comparator.
|
ObjectMatrix2D |
sort(ObjectMatrix2D matrix,
int column)
Sorts the matrix rows into ascending order, according to the natural
ordering of the matrix values in the given column.
|
ObjectMatrix2D |
sort(ObjectMatrix2D matrix,
ObjectMatrix1DComparator c)
Sorts the matrix rows according to the order induced by the specified
comparator.
|
ObjectMatrix3D |
sort(ObjectMatrix3D matrix,
int row,
int column)
Sorts the matrix slices into ascending order, according to the natural
ordering of the matrix values in the given [row,column]
position.
|
ObjectMatrix3D |
sort(ObjectMatrix3D matrix,
ObjectMatrix2DComparator c)
Sorts the matrix slices according to the order induced by the specified
comparator.
|
clonepublic static final ObjectSorting quickSort
public static final ObjectSorting mergeSort
public ObjectMatrix1D sort(ObjectMatrix1D vector)
Example:
| 7, 1, 3, 1 |
==> 1, 1, 3, 7 |
vector - the vector to be sorted.public ObjectMatrix1D sort(ObjectMatrix1D vector, Comparator c)
Example:
// sort by sinus of cells
ObjectComparator comp = new ObjectComparator() {
public int compare(Object a, Object b) {
Object as = Math.sin(a);
Object bs = Math.sin(b);
return as < bs ? -1 : as == bs ? 0 : 1;
}
};
sorted = quickSort(vector, comp);
vector - the vector to be sorted.c - the comparator to determine the order.public ObjectMatrix2D sort(ObjectMatrix2D matrix, int column)
Example:
| 4 x 2 matrix: 7, 6 5, 4 3, 2 1, 0 |
column = 0; |
4 x 2 matrix: |
matrix - the matrix to be sorted.column - the index of the column inducing the order.IndexOutOfBoundsException - if column < 0 || column >= matrix.columns().public ObjectMatrix2D sort(ObjectMatrix2D matrix, ObjectMatrix1DComparator c)
Example:
// sort by sum of values in a row
ObjectMatrix1DComparator comp = new ObjectMatrix1DComparator() {
public int compare(ObjectMatrix1D a, ObjectMatrix1D b) {
Object as = a.zSum();
Object bs = b.zSum();
return as < bs ? -1 : as == bs ? 0 : 1;
}
};
sorted = quickSort(matrix, comp);
matrix - the matrix to be sorted.c - the comparator to determine the order.public ObjectMatrix3D sort(ObjectMatrix3D matrix, int row, int column)
The algorithm compares two 2-d slices at a time, determinining whether one is smaller, equal or larger than the other. Comparison is based on the cell [row,column] within a slice. Let A and B be two 2-d slices. Then we have the following rules
matrix - the matrix to be sorted.row - the index of the row inducing the order.column - the index of the column inducing the order.IndexOutOfBoundsException - if
row < 0 || row >= matrix.rows() || column < 0 || column >= matrix.columns()
.public ObjectMatrix3D sort(ObjectMatrix3D matrix, ObjectMatrix2DComparator c)
Example:
// sort by sum of values in a slice
ObjectMatrix2DComparator comp = new ObjectMatrix2DComparator() {
public int compare(ObjectMatrix2D a, ObjectMatrix2D b) {
Object as = a.zSum();
Object bs = b.zSum();
return as < bs ? -1 : as == bs ? 0 : 1;
}
};
sorted = quickSort(matrix, comp);
matrix - the matrix to be sorted.c - the comparator to determine the order.Jump to the Parallel Colt Homepage