DoubleMatrixEncode(TextReader, Char, IndexCollection, Boolean) Method

Encodes numerical data from the stream underlying the specified text reader.

Definition

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

C#

public static DoubleMatrix Encode(
	TextReader reader,
	char columnDelimiter,
	IndexCollection extractedColumns,
	bool firstLineContainsVariableNames
)

VB

Public Shared Function Encode ( 
	reader As TextReader,
	columnDelimiter As Char,
	extractedColumns As IndexCollection,
	firstLineContainsVariableNames As Boolean
) As DoubleMatrix

C++

public:
static DoubleMatrix^ Encode(
	TextReader^ reader, 
	wchar_t columnDelimiter, 
	IndexCollection^ extractedColumns, 
	bool firstLineContainsVariableNames
)

F#

static member Encode : 
        reader : TextReader * 
        columnDelimiter : char * 
        extractedColumns : IndexCollection * 
        firstLineContainsVariableNames : bool -> DoubleMatrix

Parameters

reader TextReader: The reader having access to the data stream.
columnDelimiter Char: The delimiter used to separate columns in data lines.
extractedColumns IndexCollection: The zero-based indexes of the columns from which data are to be extracted.
firstLineContainsVariableNames Boolean: If set to true signals that the first line contains variable names.

Return Value

DoubleMatrix
The matrix containing information about the streamed data.

Remarks

Each line from the stream is interpreted as the information about variables observed at a given instance. A line is split in tokens, each corresponding to a (zero-based) column, which in turn stores the data of a given variable. Columns are assumed to be separated each other by the character passed as columnDelimiter. Data from a variable are extracted only if the corresponding column index is in the collection extractedColumns.

Data are encoded as culture independent numerical values, by applying the InvariantCulture.

Example

In the following example, a stream is read to encode numerical data into a matrix.

Encoding data into a matrix from a stream containing numerical variables

using System;
using System.IO;

namespace Novacta.Analytics.CodeExamples
{
    public class MatrixEncodeExample1  
    {
        public void Main()
        {
            // Create a data stream.
            string[] data = [
            "V0,V1,V2",
            "1, 10, -2.2",
            "2, 20,  0.0",
            "3, 30, -3.3",
            "4, 40, -1.1",
            "5, 50,  4.4" ];

            MemoryStream stream = new();
            StreamWriter writer = new(stream);
            for (int i = 0; i < data.Length; i++)
            {
                writer.WriteLine(data[i].ToCharArray());
                writer.Flush();
            }
            stream.Position = 0;

            // Encode a matrix containing columns V0 and V2.
            StreamReader streamReader = new(stream);
            char columnDelimiter = ',';
            IndexCollection extractedColumns = IndexCollection.Sequence(0, 2, 2);
            bool firstLineContainsColumnHeaders = true;
            DoubleMatrix matrix = DoubleMatrix.Encode(
                streamReader,
                columnDelimiter,
                extractedColumns,
                firstLineContainsColumnHeaders);

            // Show the matrix.
            Console.WriteLine("Encoded matrix:");
            Console.WriteLine();
            Console.Write(matrix);
            Console.WriteLine();
        }
    }
}

// Executing method Main() produces the following output:
// 
// Encoded matrix:
// 
// [V0]             [V2]             
// 1                -2.2             
// 2                0                
// 3                -3.3             
// 4                -1.1             
// 5                4.4              
// 
//

Exceptions

ArgumentNullException	reader is null. -or- extractedColumns is null.
InvalidDataException	The stream accessed by reader contains no data rows. -or- There is at least a row which contains not enough data for any column specified by extractedColumns. This can happen if there are missing columns, or if tokens extracted from the stream are null or consist only of white-space characters.