NAME

Algorithm::LibSVM - A Raku bindings for libsvm

SYNOPSIS

EXAMPLE 1

use Algorithm::LibSVM;
  use Algorithm::LibSVM::Parameter;
  use Algorithm::LibSVM::Problem;
  use Algorithm::LibSVM::Model;

my $libsvm = Algorithm::LibSVM.new;
  my Algorithm::LibSVM::Parameter $parameter .= new(svm-type => C_SVC,
                                                    kernel-type => RBF);
  # heart_scale is here: https://www.csie.ntu.edu.tw/~cjlin/libsvmtools/datasets/binary/heart_scale
  my Algorithm::LibSVM::Problem $problem = Algorithm::LibSVM::Problem.from-file('heart_scale');
  my @r = $libsvm.cross-validation($problem, $parameter, 10);
  $libsvm.evaluate($problem.y, @r).say; # {acc => 81.1111111111111, mse => 0.755555555555556, scc => 1.01157627463546}

EXAMPLE 2

use Algorithm::LibSVM;
  use Algorithm::LibSVM::Parameter;
  use Algorithm::LibSVM::Problem;
  use Algorithm::LibSVM::Model;

sub gen-train {
    my $max-x = 1;
    my $min-x = -1;
    my $max-y = 1;
    my $min-y = -1;
    my @tmp-x;
    my @tmp-y;
    do for ^300 {
        my $x = $min-x + rand * ($max-x - $min-x);
        my $y = $min-y + rand * ($max-y - $min-y);

my $label = do given $x, $y {
            when ($x - 0.5) ** 2 + ($y - 0.5) ** 2 <= 0.2 {
                1
            }
            when ($x - -0.5) ** 2 + ($y - -0.5) ** 2 <= 0.2 {
                -1
            }
            default { Nil }
        }
        if $label.defined {
            @tmp-y.push: $label;
            @tmp-x.push: [$x, $y];
        }
    }
    # Note that @x must be a shaped one.
    my @x[+@tmp-x;2] = @tmp-x.clone;
    my @y = @tmp-y.clone;
    (@x, @y)
  }

my (@train-x, @train-y) := gen-train;
  my @test-x = 1 => 0.5e0, 2 => 0.5e0;
  my $libsvm = Algorithm::LibSVM.new;
  my Algorithm::LibSVM::Parameter $parameter .= new(svm-type => C_SVC,
                                                    kernel-type => LINEAR);
  my Algorithm::LibSVM::Problem $problem = Algorithm::LibSVM::Problem.from-matrix(@train-x, @train-y);
  my $model = $libsvm.train($problem, $parameter);
  say $model.predict(features => @test-x)<label> # 1

DESCRIPTION

Algorithm::LibSVM is a Raku bindings for libsvm.

METHODS

cross-validation

Defined as:

method cross-validation(Algorithm::LibSVM::Problem $problem, Algorithm::LibSVM::Parameter $param, Int $nr-fold --> List)

Conducts $nr-fold-fold cross validation and returns predicted values.

train

Defined as:

method train(Algorithm::LibSVM::Problem $problem, Algorithm::LibSVM::Parameter $param --> Algorithm::LibSVM::Model)

Trains a SVM model.

• $problem The instance of Algorithm::LibSVM::Problem.

• $param The instance of Algorithm::LibSVM::Parameter.

DEPRECATED load-problem

Defined as:

multi method load-problem(\lines --> Algorithm::LibSVM::Problem)
        multi method load-problem(Str $filename --> Algorithm::LibSVM::Problem)

Loads libsvm-format data.

load-model

Defined as:

method load-model(Str $filename --> Algorithm::LibSVM::Model)

Loads libsvm model.

evaluate

Defined as:

method evaluate(@true-values, @predicted-values --> Hash)

Evaluates the performance of the three metrics (i.e. accuracy, mean squared error and squared correlation coefficient)

• @true-values The array that contains ground-truth values.

• @predicted-values The array that contains predicted values.

nr-feature

Defined as:

method nr-feature(--> Int:D)

Returns the maximum index of all the features.

ROUTINES

parse-libsvmformat

Defined as:

sub parse-libsvmformat(Str $text --> List) is export

Is a helper routine for handling libsvm-format text.

CAUTION

DON'T USE PRECOMPUTED KERNEL

As a workaround for RT130187, I applied the patch programs (e.g. src/3.22/svm.cpp.patch) for the sake of disabling random access of the problematic array.

Sadly to say, those patches drastically increase the complexity of using PRECOMPUTED kernel.

SEE ALSO

• libsvm https://github.com/cjlin1/libsvm

• RT130187 https://rt.perl.org/Public/Bug/Display.html?id=130187

AUTHOR

titsuki <[email protected]>

COPYRIGHT AND LICENSE

Copyright 2016 titsuki

This library is free software; you can redistribute it and/or modify it under the terms of the MIT License.

libsvm ( https://github.com/cjlin1/libsvm ) by Chih-Chung Chang and Chih-Jen Lin is licensed under the BSD 3-Clause License.