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java.lang.Object cern.colt.matrix.doublealgo.Partitioning
Given some interval boundaries, partitions matrices such that cell values falling into an interval are placed next to each other.
Performance
Partitioning into two intervals is O( N ). Partitioning into k intervals is O( N * log(k)). Constants factors are minimized.
"Partitioning arrays (provides more documentation)"
Method Summary  
static void 
partition(DoubleMatrix2D matrix,
int[] rowIndexes,
int rowFrom,
int rowTo,
int column,
double[] splitters,
int splitFrom,
int splitTo,
int[] splitIndexes)
Same as Partitioning.partition(int[],int,int,int[],int,int,int[])
except that it synchronously partitions the rows of the given matrix by the values of the given matrix column;
This is essentially the same as partitioning a list of composite objects by some instance variable;
In other words, two entire rows of the matrix are swapped, whenever two column values indicate so. 
static DoubleMatrix2D 
partition(DoubleMatrix2D matrix,
int column,
double[] splitters,
int[] splitIndexes)
Same as Partitioning.partition(int[],int,int,int[],int,int,int[])
except that it synchronously partitions the rows of the given matrix by the values of the given matrix column;
This is essentially the same as partitioning a list of composite objects by some instance variable;
In other words, two entire rows of the matrix are swapped, whenever two column values indicate so. 
Methods inherited from class java.lang.Object 
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
Method Detail 
public static void partition(DoubleMatrix2D matrix, int[] rowIndexes, int rowFrom, int rowTo, int column, double[] splitters, int splitFrom, int splitTo, int[] splitIndexes)
Partitioning.partition(int[],int,int,int[],int,int,int[])
except that it synchronously partitions the rows of the given matrix by the values of the given matrix column;
This is essentially the same as partitioning a list of composite objects by some instance variable;
In other words, two entire rows of the matrix are swapped, whenever two column values indicate so.
Let's say, a "row" is an "object" (tuple, ddimensional point). A "column" is the list of "object" values of a given variable (field, dimension). A "matrix" is a list of "objects" (tuples, points).
Now, rows (objects, tuples) are partially sorted according to their values in one given variable (dimension). Two entire rows of the matrix are swapped, whenever two column values indicate so.
Note that arguments are not checked for validity.
Example:
8 x 3 matrix: 23, 22, 21 20, 19, 18 17, 16, 15 14, 13, 12 11, 10, 9 8, 7, 6 5, 4, 3 2, 1, 0 
column = 0; 
The matrix IS NOT REORDERED. Here is how it would look like, if it would be reordered accoring to rowIndexes. 8 x 3 matrix: 2, 1, 0 5, 4, 3 8, 7, 6 11, 10, 9 23, 22, 21 20, 19, 18 17, 16, 15 14, 13, 12 
matrix
 the matrix to be partitioned.rowIndexes
 the index of the ith row; is modified by this method to reflect partitioned indexes.rowFrom
 the index of the first row (inclusive).rowTo
 the index of the last row (inclusive).column
 the index of the column to partition on.splitters
 the values at which the rows shall be split into intervals.
Must be sorted ascending and must not contain multiple identical values.
These preconditions are not checked; be sure that they are met.splitFrom
 the index of the first splitter element to be considered.splitTo
 the index of the last splitter element to be considered.
The method considers the splitter elements splitters[splitFrom] .. splitters[splitTo].splitIndexes
 a list into which this method fills the indexes of rows delimiting intervals.
Upon return splitIndexes[splitFrom..splitTo] will be set accordingly.
Therefore, must satisfy splitIndexes.length >= splitters.length.public static DoubleMatrix2D partition(DoubleMatrix2D matrix, int column, double[] splitters, int[] splitIndexes)
Partitioning.partition(int[],int,int,int[],int,int,int[])
except that it synchronously partitions the rows of the given matrix by the values of the given matrix column;
This is essentially the same as partitioning a list of composite objects by some instance variable;
In other words, two entire rows of the matrix are swapped, whenever two column values indicate so.
Let's say, a "row" is an "object" (tuple, ddimensional point). A "column" is the list of "object" values of a given variable (field, dimension). A "matrix" is a list of "objects" (tuples, points).
Now, rows (objects, tuples) are partially sorted according to their values in one given variable (dimension). Two entire rows of the matrix are swapped, whenever two column values indicate so.
Note that arguments are not checked for validity.
Example:
8 x 3 matrix: 23, 22, 21 20, 19, 18 17, 16, 15 14, 13, 12 11, 10, 9 8, 7, 6 5, 4, 3 2, 1, 0 
column = 0; splitters = {5,10,12} partition(matrix,column,splitters,splitIndexes); ==> splitIndexes == {0, 2, 3} 
The matrix IS NOT REORDERED. The new VIEW IS REORDERED: 8 x 3 matrix: 2, 1, 0 5, 4, 3 8, 7, 6 11, 10, 9 23, 22, 21 20, 19, 18 17, 16, 15 14, 13, 12 
matrix
 the matrix to be partitioned.column
 the index of the column to partition on.splitters
 the values at which the rows shall be split into intervals.
Must be sorted ascending and must not contain multiple identical values.
These preconditions are not checked; be sure that they are met.splitIndexes
 a list into which this method fills the indexes of rows delimiting intervals.
Therefore, must satisfy splitIndexes.length >= splitters.length.

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