DoubleMatrixItem(IndexCollection, String) Property

Gets or sets the elements of this instance corresponding to the specified row and column indexes.

Definition

Namespace: Novacta.Analytics
Assembly: Novacta.Analytics (in Novacta.Analytics.dll) Version: 2.1.0+428f3840cfab98dda567bb0ed350b302533e273a

C#

public DoubleMatrix this[
	IndexCollection rowIndexes,
	string columnIndexes
] { get; set; }

VB

Public Default Property Item ( 
	rowIndexes As IndexCollection,
	columnIndexes As String
) As DoubleMatrix
	Get
	Set

C++

public:
virtual property DoubleMatrix^ default[IndexCollection^ rowIndexes, String^ columnIndexes] {
	DoubleMatrix^ get (IndexCollection^ rowIndexes, String^ columnIndexes) sealed;
	void set (IndexCollection^ rowIndexes, String^ columnIndexes, DoubleMatrix^ value) sealed;
}

F#

abstract Item : DoubleMatrix with get, set
override Item : DoubleMatrix with get, set

Parameters

rowIndexes IndexCollection: The zero-based row indexes of the elements to get or set.
columnIndexes String: The zero-based column indexes of the elements to get or set. The value must be ":", which means that all valid column indexes are specified.

Property Value

DoubleMatrix
A tabular collection formed by the elements corresponding to the specified row and column indexes.

Implements

IReadOnlyTabularCollectionTValue, TCollectionItemIndexCollection, String
ITabularCollectionTValue, TCollectionItemIndexCollection, String

Remarks

When setting elements simultaneously, the value must be a tabular collection having a number of rows equal to the number of specified row indexes, and a number of columns equal to the number of specified column indexes.

Example

In the following example, some matrix elements are simultaneously accessed.

C#

using System;

namespace Novacta.Analytics.CodeExamples
{
    public class MatrixIndexerExample12  
    {
        public void Main()
        {
            // Create a matrix.
            var data = new double[12] {
                1, 5,  9,
                2, 6, 10,
                3, 7, 11,
                4, 8, 12
            };
            var matrix = DoubleMatrix.Dense(4, 3, data, StorageOrder.RowMajor);
            Console.WriteLine("Initial data matrix:");
            Console.WriteLine(matrix);

            // Specify some row indexes.
            var rowIndexes = IndexCollection.Range(1, 3);
            Console.WriteLine();
            Console.WriteLine("Row indexes: {0}", rowIndexes);

            // Specify all column indexes.
            var columnIndexes = ":";
            Console.WriteLine();
            Console.WriteLine("Column indexes: from 0 to {0}", matrix.NumberOfColumns - 1);

            // Specify the value matrix.
            var valueData = new double[9] {
              -20, -60, -100,
              -30, -70, -110,
              -40, -80, -120
            };
            var value = DoubleMatrix.Dense(3, 3, valueData, StorageOrder.RowMajor);
            Console.WriteLine();
            Console.WriteLine("Value matrix:");
            Console.WriteLine(value);

            // Set the entries having the specified indexes to the value matrix.
            matrix[rowIndexes, columnIndexes] = value;

            Console.WriteLine();
            Console.WriteLine("Updated data matrix:");
            Console.WriteLine(matrix);

            // Entries can also be accessed using a read-only wrapper 
            // of the matrix.
            ReadOnlyDoubleMatrix readOnlyMatrix = matrix.AsReadOnly();

            Console.WriteLine();
            Console.WriteLine("Updated matrix entries:");
            Console.WriteLine(readOnlyMatrix[rowIndexes, columnIndexes]);
        }
    }
}

// Executing method Main() produces the following output:
// 
// Initial data matrix:
// 1                5                9                
// 2                6                10               
// 3                7                11               
// 4                8                12               
// 
// 
// 
// Row indexes: 1, 2, 3
// 
// Column indexes: from 0 to 2
// 
// Value matrix:
// -20              -60              -100             
// -30              -70              -110             
// -40              -80              -120             
// 
// 
// 
// Updated data matrix:
// 1                5                9                
// -20              -60              -100             
// -30              -70              -110             
// -40              -80              -120             
// 
// 
// 
// Updated matrix entries:
// -20              -60              -100             
// -30              -70              -110             
// -40              -80              -120             
// 
//

Exceptions

ArgumentNullException	rowIndexes is null. -or- columnIndexes is null. -or- value is null.
ArgumentOutOfRangeException	rowIndexes contains an index which is greater than or equal to the number of rows of this instance. -or- columnIndexes is not a string reserved for tabular collection sub-referencing.
ArgumentException	The number of rows in value is not equal to the Count of rowIndexes. -or- The number of columns in value is not equal to the number of columns of this instance.