Package de.labathome.trustconstr.sparse

Class CSRMatrix.Builder

java.lang.Object

de.labathome.trustconstr.sparse.CSRMatrix.Builder

Enclosing class:

CSRMatrix

public static final class CSRMatrix.Builder
extends Object

Incremental builder for CSRMatrix using a Dictionary-of-Keys (DOK) representation under the hood. Cheap O(1) amortised set(int, int, double); build() compresses to canonical CSR (column indices sorted within each row, no duplicates).

Storing a value of exactly 0.0 via set(i, j, 0.0) removes any previously-stored entry at (i, j) so the resulting CSR contains no explicit zeros.

Method Summary

Modifier and Type	Method	Description
CSRMatrix	build()	Compress the DOK contents into a canonical CSR representation (column indices sorted within each row, no duplicates, no explicit zeros).
int	cols()
double	get(int i, int j)	Read back the value at (i, j); defaults to 0.0.
int	nnz()
int	rows()
CSRMatrix.Builder	set(int i, int j, double v)	Store v at (i, j).

Methods inherited from class java.lang.Object

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

Method Details

rows

public int rows()

Returns:

number of rows the resulting CSR will have

cols

public int cols()

Returns:

number of columns the resulting CSR will have

set

public CSRMatrix.Builder set(int i,
 int j,
 double v)

Store v at (i, j). Setting to 0.0 removes the entry. Repeated calls overwrite (this is set, not add).

Parameters:

i - 0-based row index

j - 0-based column index

v - value to store

Returns:

this builder, for chaining

get

public double get(int i,
 int j)

Read back the value at (i, j); defaults to 0.0.

Parameters:

i - 0-based row index

j - 0-based column index

Returns:

current value at (i, j), or 0.0

nnz

public int nnz()

Returns:

current number of stored non-zero entries

build

public CSRMatrix build()

Compress the DOK contents into a canonical CSR representation (column indices sorted within each row, no duplicates, no explicit zeros).

Returns:

the compressed CSRMatrix