[![Actions Status](https://github.com/frithnanth/raku-Math-Libgsl-DigitalFiltering/workflows/test/badge.svg)](https://github.com/frithnanth/raku-Math-Libgsl-DigitalFiltering/actions) [![Build Status](https://travis-ci.org/frithnanth/raku-Math-Libgsl-DigitalFiltering.svg?branch=master)](https://travis-ci.org/frithnanth/raku-Math-Libgsl-DigitalFiltering) ![Impulse filter](examples/04-impulse.svg) NAME ==== Math::Libgsl::DigitalFiltering - An interface to libgsl, the Gnu Scientific Library - Digital Filtering SYNOPSIS ======== ```raku use Math::Libgsl::Vector; use Math::Libgsl::DigitalFiltering; my constant $N = 1000; my constant $K = 21; my Math::Libgsl::Vector $x .= new: :size($N); $x.scanf('data.dat'); my Math::Libgsl::DigitalFiltering::Gaussian $gauss .= new: :size($K); my $y = $gauss.filter(2.5, $x); ``` DESCRIPTION =========== Math::Libgsl::DigitalFiltering is an interface to the Digital Filtering functions of libgsl, the Gnu Scientific Library. This module exports four classes: * Math::Libgsl::DigitalFiltering::Gaussian * Math::Libgsl::DigitalFiltering::Median * Math::Libgsl::DigitalFiltering::RMedian * Math::Libgsl::DigitalFiltering::Impulse each encapsulates the methods and the buffers needed to create and use the filter on the data stored in a Math::Libgsl::Vector object. Math::Libgsl::DigitalFiltering::Gaussian ---------------------------------------- This class encapsulate a Gaussian filter. ### multi method new(Int $size!) ### multi method new(Int :$size!) The constructor accepts one simple or named argument: the kernel size. ### filter(Num() $alpha!, Math::Libgsl::Vector $x!, Int :$order = 0, Int :$endtype = GSL_MOVSTAT_END_PADZERO, Bool :$inplace? --> Math::Libgsl::Vector) This method applies a Gaussian filter parameterized by **$alpha** to the input vector **$x**. The optional named argument **:$order** specifies the derivative order, with `0` corresponding to a Gaussian, `1` corresponding to a first derivative Gaussian, and so on. The optional named argument **:$endtype** specifies how the signal end points are handled. The symbolic names for this argument are listed in the Math::Libgsl::Constants module as follows: * **GSL_MOVSTAT_END_PADZERO**: inserts zeros into the window near the signal end points * **GSL_MOVSTAT_END_PADVALUE**: pads the window with the first and last sample in the input signal * **GSL_MOVSTAT_END_TRUNCATE**: no padding is performed: the windows are truncated as the end points are approached The boolean named argument **:$inplace** directs the method to apply the filter in-place. This method returns the filter output as a **Math::Libgsl::Vector** object. ### kernel(Num() $alpha!, Int $size, Int :$order = 0, Int :$normalize = 0 --> Math::Libgsl::Vector) This method constructs a Gaussian kernel parameterized by **$alpha**, of size **$size**. The optional named argument **:$order** specifies the derivative order. The optional named argument **:$normalize** specifies if the kernel is to be normalized to sum to one on output. This method returns the filter output as a **Math::Libgsl::Vector** object. Math::Libgsl::DigitalFiltering::Median -------------------------------------- This class encapsulate a Median filter. ### multi method new(Int $size!) ### multi method new(Int :$size!) The constructor accepts one simple or named argument: the kernel size. ### filter(Math::Libgsl::Vector $x!, Int :$endtype = GSL_MOVSTAT_END_PADZERO, Bool :$inplace? --> Math::Libgsl::Vector) This method applies a Median filter to the input vector **$x**. The optional named argument **:$endtype** specifies how the signal end points are handled. The optional boolean named argument **:$inplace** directs the method to apply the filter in-place. This method returns the filter output as a **Math::Libgsl::Vector** object. Math::Libgsl::DigitalFiltering::RMedian --------------------------------------- This class encapsulate a recursive Median filter. ### multi method new(Int $size!) ### multi method new(Int :$size!) The constructor accepts one simple or named argument: the kernel size. ### filter(Math::Libgsl::Vector $x!, Int :$endtype = GSL_MOVSTAT_END_PADZERO, Bool :$inplace? --> Math::Libgsl::Vector) This method applies a Median filter to the input vector **$x**. The optional named argument **:$endtype** specifies how the signal end points are handled. The optional boolean named argument **:$inplace** directs the method to apply the filter in-place. This method returns the filter output as a **Math::Libgsl::Vector** object. Math::Libgsl::DigitalFiltering::Impulse --------------------------------------- This class encapsulate an Impulse detection filter. ### multi method new(Int $size!) ### multi method new(Int :$size!) The constructor accepts one simple or named argument: the kernel size. ### filter(Math::Libgsl::Vector $x!, Num() $tuning, Int :$endtype = GSL_MOVSTAT_END_PADZERO, Int :$scaletype = GSL_FILTER_SCALE_MAD, Bool :$inplace? --> List) This method applies an Impulse filter to the input vector **$x**, using the tuning parameter **$tuning**. The optional named argument **:$endtype** specifies how the signal end points are handled. The optional named argument **:$scaletype** specifies how the scale estimate Sₙ of the window is calculated. The symbolic names for this argument are listed in the Math::Libgsl::Constants module as follows: * **GSL_FILTER_SCALE_MAD**: specifies the median absolute deviation (MAD) scale estimate * **GSL_FILTER_SCALE_IQR**: specifies the interquartile range (IQR) scale estimate * **GSL_FILTER_SCALE_SN**: specifies the so-called Sₙ statistic * **GSL_FILTER_SCALE_QN**: specifies the so-called Qₙ statistic The optional boolean named argument **:$inplace** directs the method to apply the filter in-place. This method returns a List of values: * the window medians, as a **Math::Libgsl::Vector** object * the window Sₙ, as a **Math::Libgsl::Vector** object * the number of outliers as an Int * the location of the outliers as a **Math::Libgsl::Vector::Int32** object C Library Documentation ======================= For more details on libgsl see [https://www.gnu.org/software/gsl/](https://www.gnu.org/software/gsl/). The excellent C Library manual is available here [https://www.gnu.org/software/gsl/doc/html/index.html](https://www.gnu.org/software/gsl/doc/html/index.html), or here [https://www.gnu.org/software/gsl/doc/latex/gsl-ref.pdf](https://www.gnu.org/software/gsl/doc/latex/gsl-ref.pdf) in PDF format. Prerequisites ============= This module requires the libgsl library to be installed. Please follow the instructions below based on your platform: Debian Linux and Ubuntu 20.04 ----------------------------- sudo apt install libgsl23 libgsl-dev libgslcblas0 That command will install libgslcblas0 as well, since it's used by the GSL. Ubuntu 18.04 ------------ libgsl23 and libgslcblas0 have a missing symbol on Ubuntu 18.04. I solved the issue installing the Debian Buster version of those three libraries: * [http://http.us.debian.org/debian/pool/main/g/gsl/libgslcblas0_2.5+dfsg-6_amd64.deb](http://http.us.debian.org/debian/pool/main/g/gsl/libgslcblas0_2.5+dfsg-6_amd64.deb) * [http://http.us.debian.org/debian/pool/main/g/gsl/libgsl23_2.5+dfsg-6_amd64.deb](http://http.us.debian.org/debian/pool/main/g/gsl/libgsl23_2.5+dfsg-6_amd64.deb) * [http://http.us.debian.org/debian/pool/main/g/gsl/libgsl-dev_2.5+dfsg-6_amd64.deb](http://http.us.debian.org/debian/pool/main/g/gsl/libgsl-dev_2.5+dfsg-6_amd64.deb) Installation ============ To install it using zef (a module management tool): $ zef install Math::Libgsl::DigitalFiltering AUTHOR ====== Fernando Santagata COPYRIGHT AND LICENSE ===================== Copyright 2020 Fernando Santagata This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.