Imports System Imports System.IO Imports System.Collections Imports CenterSpace.NMath.Core Namespace CenterSpace.NMath.Core.Examples.VisualBasic ' A .NET example in Visual Basic showing how to use the linear regression class to perform a simple ' linear regression. ' A simple linear regression fits a straight line through a series of data ' points. Specifically, the points <c>(x,y)</c> are assumed to conform to ' the equation <c>y = mx + b</c>. A simple linear regression uses a least ' squares fit to compute the slope, <c>m</c>, and the y-intercept, <c>b</c>. Module SimpleLinearRegressionExample Sub Main() ' Read in data from the file. The data comes from The Data and Story ' Library (http:'lib.stat.cmu.edu/DASL) and is described below: ' ' Results of a study of gas chromatography, a technique which is used ' to detect very small amounts of a substance. Five measurements were ' taken for each of four specimens containing different amounts of the ' substance. The amounts of the substance in each specimen was determined ' before the experiment. The responses variable is the output reading ' from the gas chromatograph. The purpose of the study is to calibrate ' the chromatograph by relating the actual amounts of the substance to ' the chromatograph reading. Dim DataStream As New StreamReader("SimpleLinearRegressionExample.dat") ' First read in the independent (or predictor) values. This is a matrix ' with one column and a row for each amounts measurement. Dim Amounts As DoubleMatrix = New DoubleMatrix(DataStream) ' Next, read in the responses. These are the readings of the gas ' chromatograph Dim Responses As DoubleVector = New DoubleVector(DataStream) ' Print out the amounts and responses values. Console.WriteLine() Console.WriteLine("amounts = " & Amounts.ToString()) Console.WriteLine("responses = " & Responses.ToString()) ' Construct a linear regression. If we want our regression to calculate a ' y-intercept we must send in true for the "addIntercept" parameter (the ' third parameter in the constructor). Dim Regression As LinearRegression = New LinearRegression(Amounts, Responses, True) ' The y-intercept is the first element of the parameter array returned by ' the regression, and the slope is the second. Console.WriteLine("y-intercept = " & Regression.Parameters(0)) Console.WriteLine("Slope = " & Regression.Parameters(1)) ' What would the model predict for the chromatograph reading for an ' input amounts of 0.75 and 1.25? Dim Amount As DoubleVector = New DoubleVector(0.75) Dim PredictedReading As Double = Regression.PredictedObservation(Amount) Console.WriteLine("Predicted reading for amount " & Amount(0) & " is " & PredictedReading) Amount(0) = 1.25 PredictedReading = Regression.PredictedObservation(Amount) Console.WriteLine("Predicted reading for amount " & Amount(0) & " is " & PredictedReading) ' Let's look at the coefficient of determination for the model - Rsquared. ' To do this we will need to construct an Analysis Of VAriance object for ' the regression. Dim RegressionAnova As New LinearRegressionAnova(Regression) Console.WriteLine("Rsquare = " & RegressionAnova.RSquared) Console.WriteLine() Console.WriteLine("Press Enter Key") Console.Read() End Sub End Module End Namespace← All NMath Stats Code Examples