public class FloatSorting 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 FloatSorting |
mergeSort
A prefabricated mergesort.
|
static FloatSorting |
quickSort
A prefabricated quicksort.
|
| Modifier and Type | Method and Description |
|---|---|
static void |
main(String[] args) |
FloatMatrix1D |
sort(FloatMatrix1D vector)
Sorts the vector into ascending order, according to the natural
ordering.
|
FloatMatrix1D |
sort(FloatMatrix1D vector,
FloatComparator c)
Sorts the vector into ascending order, according to the order induced by
the specified comparator.
|
FloatMatrix2D |
sort(FloatMatrix2D matrix,
float[] aggregates)
Sorts the matrix rows into ascending order, according to the natural
ordering of the matrix values in the virtual column
aggregates; Particularly efficient when comparing expensive
aggregates, because aggregates need not be recomputed time and again, as
is the case for comparator based sorts.
|
FloatMatrix2D |
sort(FloatMatrix2D matrix,
FloatBinFunction1D aggregate)
Sorts the matrix rows into ascending order, according to the natural
ordering of the values computed by applying the given aggregation
function to each row; Particularly efficient when comparing expensive
aggregates, because aggregates need not be recomputed time and again, as
is the case for comparator based sorts.
|
FloatMatrix2D |
sort(FloatMatrix2D matrix,
FloatMatrix1DComparator c)
Sorts the matrix rows according to the order induced by the specified
comparator.
|
FloatMatrix2D |
sort(FloatMatrix2D matrix,
int column)
Sorts the matrix rows into ascending order, according to the natural
ordering of the matrix values in the given column.
|
FloatMatrix3D |
sort(FloatMatrix3D matrix,
FloatMatrix2DComparator c)
Sorts the matrix slices according to the order induced by the specified
comparator.
|
FloatMatrix3D |
sort(FloatMatrix3D 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.
|
int[] |
sortIndex(FloatMatrix1D vector)
Sorts indexes of the
vector into ascending order. |
int[] |
sortIndex(FloatMatrix1D vector,
FloatComparator c)
Sorts indexes of the
vector according to the comparator
c. |
int[] |
sortIndex(FloatMatrix1D vector,
IntComparator comp)
Multithreaded method that sorts indexes of the
vector
according to the comparator comp. |
static void |
zdemo1()
Demonstrates advanced sorting.
|
static void |
zdemo2()
Demonstrates advanced sorting.
|
static void |
zdemo3()
Demonstrates advanced sorting.
|
static void |
zdemo5(int rows,
int columns,
boolean print)
Demonstrates sorting with precomputation of aggregates (median and sum of
logarithms).
|
static void |
zdemo6()
Demonstrates advanced sorting.
|
static void |
zdemo7(int rows,
int columns,
boolean print)
Demonstrates sorting with precomputation of aggregates, comparing
mergesort with quicksort.
|
static void |
zdemo8(int size) |
clonepublic static final FloatSorting quickSort
public static final FloatSorting mergeSort
public FloatMatrix1D sort(FloatMatrix1D vector)
Example:
| 7, 1, 3, 1 |
==> 1, 1, 3, 7 |
vector - the vector to be sorted.public int[] sortIndex(FloatMatrix1D vector)
vector into ascending order.vector - public int[] sortIndex(FloatMatrix1D vector, IntComparator comp)
vector
according to the comparator comp.vector - comp - public FloatMatrix1D sort(FloatMatrix1D vector, FloatComparator c)
Example:
// sort by sinus of cells
FloatComparator comp = new FloatComparator() {
public int compare(float a, float b) {
float as = Math.sin(a);
float 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 int[] sortIndex(FloatMatrix1D vector, FloatComparator c)
vector according to the comparator
c.vector - c - public FloatMatrix2D sort(FloatMatrix2D matrix, float[] aggregates)
The returned view is backed by this matrix, so changes in the returned view are reflected in this matrix, and vice-versa. To sort ranges use sub-ranging views. To sort columns by rows, use dice views. To sort descending, use flip views ...
Example: Each aggregate is the sum of a row
| 4 x 2 matrix: 1, 1 5, 4 3, 0 4, 4 |
aggregates= 2 9 3 8 ==> |
4 x 2 matrix: |
// sort 10000 x 1000 matrix by sum of logarithms in a row (i.e. by geometric mean)
FloatMatrix2D matrix = new DenseFloatMatrix2D(10000, 1000);
matrix.assign(new cern.jet.random.engine.MersenneTwister()); // initialized randomly
cern.jet.math.Functions F = cern.jet.math.Functions.functions; // alias for convenience
// THE QUICK VERSION (takes some 3 secs)
// aggregates[i] = Sum(log(row));
float[] aggregates = new float[matrix.rows()];
for (int i = matrix.rows(); --i >= 0;)
aggregates[i] = matrix.viewRow(i).aggregate(F.plus, F.log);
FloatMatrix2D sorted = quickSort(matrix, aggregates);
// THE SLOW VERSION (takes some 90 secs)
FloatMatrix1DComparator comparator = new FloatMatrix1DComparator() {
public int compare(FloatMatrix1D x, FloatMatrix1D y) {
float a = x.aggregate(F.plus, F.log);
float b = y.aggregate(F.plus, F.log);
return a < b ? -1 : a == b ? 0 : 1;
}
};
FloatMatrix2D sorted = quickSort(matrix, comparator);
|
matrix - the matrix to be sorted.aggregates - the values to sort on. (As a side effect, this array will also
get sorted).IndexOutOfBoundsException - if aggregates.length != matrix.rows().public FloatMatrix2D sort(FloatMatrix2D 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 FloatMatrix2D sort(FloatMatrix2D matrix, FloatMatrix1DComparator c)
Example:
// sort by sum of values in a row
FloatMatrix1DComparator comp = new FloatMatrix1DComparator() {
public int compare(FloatMatrix1D a, FloatMatrix1D b) {
float as = a.zSum();
float 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 FloatMatrix2D sort(FloatMatrix2D matrix, FloatBinFunction1D aggregate)
The returned view is backed by this matrix, so changes in the returned view are reflected in this matrix, and vice-versa. To sort ranges use sub-ranging views. To sort columns by rows, use dice views. To sort descending, use flip views ...
Example: Each aggregate is the sum of a row
| 4 x 2 matrix: 1, 1 5, 4 3, 0 4, 4 |
aggregates= hep.aida.bin.BinFunctions1D.sum ==> |
4 x 2 matrix: |
// sort 10000 x 1000 matrix by median or by sum of logarithms in a row (i.e. by geometric mean)
FloatMatrix2D matrix = new DenseFloatMatrix2D(10000, 1000);
matrix.assign(new cern.jet.random.engine.MersenneTwister()); // initialized randomly
cern.jet.math.Functions F = cern.jet.math.Functions.functions; // alias for convenience
// THE QUICK VERSION (takes some 10 secs)
FloatMatrix2D sorted = quickSort(matrix, hep.aida.bin.BinFunctions1D.median);
//FloatMatrix2D sorted = quickSort(matrix,hep.aida.bin.BinFunctions1D.sumOfLogarithms);
// THE SLOW VERSION (takes some 300 secs)
FloatMatrix1DComparator comparator = new FloatMatrix1DComparator() {
public int compare(FloatMatrix1D x, FloatMatrix1D y) {
float a = cern.colt.matrix.floatalgo.Statistic.bin(x).median();
float b = cern.colt.matrix.floatalgo.Statistic.bin(y).median();
// float a = x.aggregate(F.plus,F.log);
// float b = y.aggregate(F.plus,F.log);
return a < b ? -1 : a == b ? 0 : 1;
}
};
FloatMatrix2D sorted = quickSort(matrix, comparator);
|
matrix - the matrix to be sorted.aggregate - the function to sort on; aggregates values in a row.public FloatMatrix3D sort(FloatMatrix3D 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 FloatMatrix3D sort(FloatMatrix3D matrix, FloatMatrix2DComparator c)
Example:
// sort by sum of values in a slice
FloatMatrix2DComparator comp = new FloatMatrix2DComparator() {
public int compare(FloatMatrix2D a, FloatMatrix2D b) {
float as = a.zSum();
float 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 static void zdemo1()
public static void zdemo2()
public static void zdemo3()
public static void zdemo5(int rows,
int columns,
boolean print)
public static void zdemo6()
public static void zdemo7(int rows,
int columns,
boolean print)
public static void zdemo8(int size)
public static void main(String[] args)
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