org.openuat.features
Class QuantizedFFTCoefficients

java.lang.Object
  org.openuat.features.QuantizedFFTCoefficients

public class QuantizedFFTCoefficients
extends java.lang.Object

This class computes quantized FFT coefficients from time series / sensor signals. There are 4 types that can be computed, a combination of: - linear or exponential quantization bands - quantize either FFT coefficients directly or their pairwise sums

Version:

1.0

Author:

Rene Mayrhofer

Constructor Summary

QuantizedFFTCoefficients()

Method Summary

static int[][]	computeFFTCoefficientsCandidates(double[] segment, int offset, int numFFTPoints, int numFFTCoeffCompared, int numQuantLevels, int numCandidates, boolean addPairwise, boolean exponentialBands) Computes cofficient vector candidates, quantized with different offsets.
static boolean[]	quantizeAndCompare(double[] vector1, double[] vector2, int offset, int numFFTPoints, int numFFTCoeffCompared, int numQuantLevels, int numCandidates) This is a helper function to compute and compare all 4 types.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

QuantizedFFTCoefficients

public QuantizedFFTCoefficients()

Method Detail

computeFFTCoefficientsCandidates

public static int[][] computeFFTCoefficientsCandidates(double[] segment,
                                                       int offset,
                                                       int numFFTPoints,
                                                       int numFFTCoeffCompared,
                                                       int numQuantLevels,
                                                       int numCandidates,
                                                       boolean addPairwise,
                                                       boolean exponentialBands)

Computes cofficient vector candidates, quantized with different offsets.

Parameters:

segment - The segment to compute quantized FFT coefficients on.

offset - Elements of segment will be used starting with this index.

numFFTPoints - The number of FFT points for computing the coefficients. This is the number of samples used from segment.

numFFTCoeffCompared - The number of FFT coefficients to output.

numQuantLevels - The number of quantization levels to use.

numCandidates - The number of candidates to generate with different quantization offsets.

doDirect - If true, the FFT coefficients will be used directly.

doPairwise - If true, the FFT coefficients will be added pairwise.

doLinear - If true, linear quantization bands will be used.

doExponential - If true, exponential quantization bands will be used.

Returns:

An array of quantized FFT coefficients, which are the multiple candidates. That is, the returned array has numCandidates elements, which are arrays of len integers.

quantizeAndCompare

public static boolean[] quantizeAndCompare(double[] vector1,
                                           double[] vector2,
                                           int offset,
                                           int numFFTPoints,
                                           int numFFTCoeffCompared,
                                           int numQuantLevels,
                                           int numCandidates)

This is a helper function to compute and compare all 4 types.

Returns:

An boolean array of 4 elements, true when the respective type contains at least one match among the candidates.