StatMean(ReadOnlyDoubleMatrix, DataOperation) Method

Returns the arithmetic mean of each row or column in the specified data.

Definition

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

C#

public static DoubleMatrix Mean(
	ReadOnlyDoubleMatrix data,
	DataOperation dataOperation
)

VB

Public Shared Function Mean ( 
	data As ReadOnlyDoubleMatrix,
	dataOperation As DataOperation
) As DoubleMatrix

C++

public:
static DoubleMatrix^ Mean(
	ReadOnlyDoubleMatrix^ data, 
	DataOperation dataOperation
)

F#

static member Mean : 
        data : ReadOnlyDoubleMatrix * 
        dataOperation : DataOperation -> DoubleMatrix

Parameters

data ReadOnlyDoubleMatrix: The data.
dataOperation DataOperation: A constant to specify if the arithmetic mean is to be computed for rows or columns.

Return Value

DoubleMatrix
The arithmetic mean of each row or column in the specified data.

Remarks

This method returns the arithmetic mean of data rows or columns. Let LaTeX equation and be the data number of rows and columns, respectively, and define

Operating on rows

If dataOperation is OnRows, then the method returns a column vector whose length equals the number of rows of data. The i-th entry of the returned column exposes the arithmetic mean of the i-th data row.

The arithmetic mean of the i-th row can be represented by the expression

LaTeX equation

Operating on columns

If dataOperation is OnColumns, then the method returns a row vector whose length is the data number of columns. The j-th entry of the returned row exposes the mean of the j-th data column.

The arithmetic mean of the j-th column can be represented by the expression

LaTeX equation

Example

In the following example, row and column arithmetic means in a data matrix are computed.

C#

using System;

namespace Novacta.Analytics.CodeExamples
{
    public class MeanExample0  
    {
        public void Main()
        {
            // Create a matrix.
            var data = new double[6] {
                1, 2,
                2, 3,
                3, 4
            };
            var matrix = DoubleMatrix.Dense(3, 2, data, StorageOrder.RowMajor);
            Console.WriteLine("The data matrix:");
            Console.WriteLine(matrix);

            // Compute the mean on columns.
            var meanOnColumns = Stat.Mean(matrix, DataOperation.OnColumns);

            Console.WriteLine();
            Console.WriteLine("Mean on columns:");
            Console.WriteLine(meanOnColumns);

            // Mean is overloaded to accept data as a read-only matrix:
            // compute the mean on rows using a read-only wrapper of the data matrix.
            ReadOnlyDoubleMatrix readOnlyMatrix = matrix.AsReadOnly();
            var meanOnRows = Stat.Mean(readOnlyMatrix, DataOperation.OnRows);

            Console.WriteLine();
            Console.WriteLine("Mean on rows:");
            Console.WriteLine(meanOnRows);
        }
    }
}

// Executing method Main() produces the following output:
// 
// The data matrix:
// 1                2                
// 2                3                
// 3                4                
// 
// 
// 
// Mean on columns:
// 2                3                
// 
// 
// 
// Mean on rows:
// 1.5              
// 2.5              
// 3.5              
// 
//

Exceptions

ArgumentNullException	data is null.
ArgumentException	dataOperation is not a field of DataOperation.