dp3::ddecal::KernelSmoother< DataType, NumType > Class Template Reference

Smooths a series of possibly irregularly gridded values by a given kernel. More...

#include <KernelSmoother.h>

Public Types
enum	KernelType { RectangularKernel , TriangularKernel , GaussianKernel , EpanechnikovKernel }

Public Member Functions
	KernelSmoother (const std::vector< NumType > &frequencies, KernelType kernelType, NumType kernelBandwidth, NumType bandwidthRefFrequency, NumType spectralExponent, bool kernel_truncation)
NumType	Kernel (NumType distance) const
void	Smooth (DataType *data, const NumType *weight, NumType kernelSizeFactor)

Detailed Description

template<typename DataType, typename NumType>
class dp3::ddecal::KernelSmoother< DataType, NumType >

Smooths a series of possibly irregularly gridded values by a given kernel.

The class is optimized to smooth many series which are all placed on the same grid. This is the case when smoothing the solutions on a (a possibly irregular) channel grid.

This class uses internally stored scratch space, and is therefore not thread safe. To smooth with multiple threads, instantiate a KernelSmoother for each thread.

Member Enumeration Documentation

KernelType

template<typename DataType , typename NumType >

enum dp3::ddecal::KernelSmoother::KernelType

Enumerator
RectangularKernel
TriangularKernel
GaussianKernel	Gaussian, trimmed off at 3 sigma
EpanechnikovKernel	The Epanechnikov kernel is a quadratic kernel, given by 3/4 (1 - x^2)

Constructor & Destructor Documentation

KernelSmoother()

template<typename DataType , typename NumType >

dp3::ddecal::KernelSmoother< DataType, NumType >::KernelSmoother ( const std::vector< NumType > &  frequencies, KernelType  kernelType, NumType  kernelBandwidth, NumType  bandwidthRefFrequency, NumType  spectralExponent, bool  kernel_truncation  )

inline

Construct and initialize kernel smoother. With se the spectralExponent, s the kernelBandwidth, nu the frequency at which to evaluate the kernel the kernel size is calculated as: s(nu) = (nu_0 / nu) ^ se

Parameters

frequencies	Vector defining the channel frequencies: frequencies[i] specifies the frequency of channel i in Hz. The size of this vector (number of channels) defines the size of the grid n.
kernelType	Type of kernel to use for smoothing
kernelBandwidth	Size of the kernel (smoothing strength) in frequency units (Hz). May be 0.0 to disable frequency correction of the kernel size.
bandwidthRefFrequency	If non-zero, sets the frequency value at which the kernel size equals the specified size with kernelBandwidth.
spectralExponent	A value that specifies the exponent in the relative spectral factor of the kernel size.

Member Function Documentation

Kernel()

template<typename DataType , typename NumType >

NumType dp3::ddecal::KernelSmoother< DataType, NumType >::Kernel ( NumType  distance ) const

inline

Evaluate the kernel for a given position.

Parameters

distance

Distance (positive or negative) from centre of the kernel to evaluate the kernel for, in units of frequency (Hz).

Returns

Unnormalized kernel value (i.e., integral of kernel is not necessarily unity).

e^(-x^2 / sigma^2), sigma = bandwidth / 3.

3/4 * (1-x)^2;

Smooth()

template<typename DataType , typename NumType >

void dp3::ddecal::KernelSmoother< DataType, NumType >::Smooth ( DataType *  data, const NumType *  weight, NumType  kernelSizeFactor  )

inline

Replaces the data with a smoothed version of the data.

Parameters

data	Data array of size n (as specified in constructor) that is smoothed on output.
weight	Associated weights, array of size n.
kernelSizeFactor	A factor that is applied to the frequency axis, such that a larger factors causes less smoothing.

find right-most kernel value corresponding to the first element of data

If a boundary is further than half the bandwidth away, move boundary

A value of 1 is added to make sure we are not skipping a value because of rounding errors (kernel will correctly evaluate past boundaries, so including an unnecessary value has no effect)

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The documentation for this class was generated from the following file:

• KernelSmoother.h