Abstractions csrmatrix constructor

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CsrMatrix(rowCount, columnCount, values, columnIndices, rowPointers)

Builds a matrix from its three arrays, checking that they describe one: the boundary a matrix read from a file, a network or a caller crosses.

public CsrMatrix(int rowCount, int columnCount, double[] values, int[] columnIndices, int[] rowPointers)

Parameters — rowCount and columnCount are the logical shape, zeros included. values holds the stored cells, row by row, and columnIndices the column of each. rowPointers holds rowCount + 1 entries: where each row starts in values, then the stored count.

Returns — the matrix, sharing the three arrays: they are taken as they are, not copied.

Exceptions — ArgumentNullException when an array is null. ArgumentOutOfRangeException when rowCount or columnCount is negative. ArgumentException when the arrays do not describe a matrix: rowPointers does not hold rowCount + 1 entries, values and columnIndices differ in length, the first row pointer is not 0, a pointer decreases, the last is not the stored count, or a column index is outside [0, columnCount).

Example — a 2 × 3 matrix storing three cells.

using Lodestar.Abstractions;

var matrix = new CsrMatrix(
    rowCount: 2,
    columnCount: 3,
    values: [1.0, 2.0, 3.0],
    columnIndices: [0, 2, 1],
    rowPointers: [0, 2, 3]);

int stored = matrix.NonZeroCount;     // => 3
double second = matrix.RowL1Norm(1);  // => 3

Remarks — every refused shape is a case in CsrMatrixValidationTests. A column stored twice in one row is accepted, and read as scipy reads it; CsrMatrix says which members sum the two. CsrMatrix.CreateUnchecked skips the per-entry pass for arrays valid by construction.

Applies to — net10.0, netstandard2.0.

See also — CsrMatrix, CsrMatrix.CreateUnchecked.