/// <summary>
/// Multilevel 1-D Discreete Wavelet Transform
/// </summary>
/// <param name="signal">The signal. Example: new Signal(5, 6, 7, 8, 1, 2, 3, 4)</param>
/// <param name="motherWavelet">The mother wavelet to be used. Example: CommonMotherWavelets.GetWaveletFromName("DB4")</param>
/// <param name="level">The depth-level to perform the DWT</param>
/// <param name="extensionMode">Signal extension mode</param>
/// <param name="convolutionMode">Defines what convolution function should be used</param>
/// <returns></returns>
public static List <DecompositionLevel> ExecuteDWT(Signal signal, MotherWavelet motherWavelet, int level, SignalExtension.ExtensionMode extensionMode = SignalExtension.ExtensionMode.SymmetricHalfPoint, ConvolutionModeEnum convolutionMode = ConvolutionModeEnum.ManagedFFT)
{
var levels = new List <DecompositionLevel>();
var approximation = (double[])signal.Samples.Clone();
var details = (double[])signal.Samples.Clone();
var realLength = signal.Samples.Length;
for (var i = 1; i <= level; i++)
{
var extensionSize = motherWavelet.Filters.DecompositionLowPassFilter.Length - 1;
approximation = SignalExtension.Extend(approximation, extensionMode, extensionSize);
details = SignalExtension.Extend(details, extensionMode, extensionSize);
approximation = WaveMath.Convolve(convolutionMode, approximation, motherWavelet.Filters.DecompositionLowPassFilter);
approximation = WaveMath.DownSample(approximation);
details = WaveMath.Convolve(convolutionMode, details, motherWavelet.Filters.DecompositionHighPassFilter);
details = WaveMath.DownSample(details);
realLength = realLength / 2;
levels.Add(new DecompositionLevel
{
Signal = signal,
Index = i - 1,
Approximation = approximation,
Details = details
});
details = (double[])approximation.Clone();
}
return(levels);
}
/// <summary>
/// Executes the block
/// </summary>
public override void Execute()
{
var inputNode = InputNodes[0].ConnectingNode as BlockOutputNode;
if (inputNode == null || inputNode.Object == null)
{
return;
}
OutputNodes[0].Object.Clear();
foreach (var inputSignal in inputNode.Object)
{
var ifft = (double[])inputSignal.Samples.Clone();
ManagedFFT.Instance.FFT(ref ifft, false, Mode);
ifft = WaveMath.DownSample(ifft, 2, true);
var signal = new Signal(ifft)
{
Start = 0,
Finish = ifft.Length - 1,
SamplingInterval = 1
};
OutputNodes[0].Object.Add(signal);
}
if (Cascade && OutputNodes[0].ConnectingNode != null)
{
OutputNodes[0].ConnectingNode.Root.Execute();
}
}
public void TestDownsample()
{
var input = new double[] { 1, 2, 3, 4, 5, 6, 7, 8 };
var downSampled = WaveMath.DownSample(input);
var expected = new double[] { 2, 4, 6, 8 };
Assert.IsTrue(downSampled.SequenceEqual(expected));
input = new double[] { 1, 2, 3 };
downSampled = WaveMath.DownSample(input);
expected = new double[] { 2 };
Assert.IsTrue(downSampled.SequenceEqual(expected));
input = new double[] { 1 };
downSampled = WaveMath.DownSample(input);
expected = new double[] { };
Assert.IsTrue(downSampled.SequenceEqual(expected));
}
/// <summary>
/// Executes the block
/// </summary>
public override void Execute()
{
var inputNode = InputNodes[0].ConnectingNode as BlockOutputNode;
if (inputNode == null || inputNode.Object == null)
{
return;
}
OutputNodes[0].Object.Clear();
foreach (var signal in inputNode.Object)
{
var output = signal.Copy();
output.Samples = WaveMath.DownSample(signal.Samples, Convert.ToInt32(Factor), true);
OutputNodes[0].Object.Add(output);
}
if (Cascade && OutputNodes[0].ConnectingNode != null)
{
OutputNodes[0].ConnectingNode.Root.Execute();
}
}
