Add a SvmDataset class for SVM-Light (or LibSVM) format files (#237)

* Add data loader for svm format

* Add tests for error cases

* Set proper exception messages

* Add documents

* Add error checking code for invalid column format

* Add missing documents

README.md

@@ -104,6 +104,7 @@ Example scripts are available in a separate repository [php-ai/php-ml-examples](
     * [Array](http://php-ml.readthedocs.io/en/latest/machine-learning/datasets/array-dataset/)
     * [CSV](http://php-ml.readthedocs.io/en/latest/machine-learning/datasets/csv-dataset/)
     * [Files](http://php-ml.readthedocs.io/en/latest/machine-learning/datasets/files-dataset/)
+    * [SVM](http://php-ml.readthedocs.io/en/latest/machine-learning/datasets/svm-dataset/)
     * Ready to use:
         * [Iris](http://php-ml.readthedocs.io/en/latest/machine-learning/datasets/demo/iris/)
         * [Wine](http://php-ml.readthedocs.io/en/latest/machine-learning/datasets/demo/wine/)

docs/index.md

@@ -12,7 +12,7 @@
 <a href="http://www.yegor256.com/2016/10/23/award-2017.html">
   <img src="http://www.yegor256.com/images/award/2017/winner-itcraftsmanpl.png"
   style="width:203px;height:45px;"/></a>
-  
+
 ![PHP-ML - Machine Learning library for PHP](assets/php-ml-logo.png)
 
 Fresh approach to Machine Learning in PHP. Algorithms, Cross Validation, Neural Network, Preprocessing, Feature Extraction and much more in one library.
@@ -31,7 +31,7 @@ $labels = ['a', 'a', 'a', 'b', 'b', 'b'];
 $classifier = new KNearestNeighbors();
 $classifier->train($samples, $labels);
 
-$classifier->predict([3, 2]); 
+$classifier->predict([3, 2]);
 // return 'b'
 ```
 
@@ -89,6 +89,7 @@ Example scripts are available in a separate repository [php-ai/php-ml-examples](
     * [Array](machine-learning/datasets/array-dataset.md)
     * [CSV](machine-learning/datasets/csv-dataset.md)
     * [Files](machine-learning/datasets/files-dataset.md)
+    * [SVM](machine-learning/datasets/svm-dataset.md)
     * Ready to use:
         * [Iris](machine-learning/datasets/demo/iris.md)
         * [Wine](machine-learning/datasets/demo/wine.md)
@@ -100,7 +101,7 @@ Example scripts are available in a separate repository [php-ai/php-ml-examples](
     * [Matrix](math/matrix.md)
     * [Set](math/set.md)
     * [Statistic](math/statistic.md)
-    
+
 
 ## Contribute
 

docs/machine-learning/datasets/svm-dataset.md

@@ -0,0 +1,13 @@
+# SvmDataset
+
+Helper class that loads data from SVM-Light format file. It extends the `ArrayDataset`.
+
+### Constructors Parameters
+
+* $filepath - (string) path to the file
+
+```
+$dataset = new SvmDataset('dataset.svm');
+```
+
+See [ArrayDataset](array-dataset.md) for more information.

mkdocs.yml

@@ -38,6 +38,7 @@ pages:
       - Array Dataset: machine-learning/datasets/array-dataset.md
       - CSV Dataset: machine-learning/datasets/csv-dataset.md
       - Files Dataset: machine-learning/datasets/files-dataset.md
+      - SVM Dataset: machine-learning/datasets/svm-dataset.md
       - Ready to use datasets:
         - Iris: machine-learning/datasets/demo/iris.md
         - Wine: machine-learning/datasets/demo/wine.md

src/Dataset/SvmDataset.php

@@ -0,0 +1,130 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Phpml\Dataset;
+
+use Phpml\Exception\DatasetException;
+use Phpml\Exception\FileException;
+
+class SvmDataset extends ArrayDataset
+{
+    public function __construct(string $filePath)
+    {
+        [$samples, $targets] = self::readProblem($filePath);
+
+        parent::__construct($samples, $targets);
+    }
+
+    private static function readProblem(string $filePath): array
+    {
+        $handle = self::openFile($filePath);
+
+        $samples = [];
+        $targets = [];
+        $maxIndex = 0;
+        while (($line = fgets($handle)) !== false) {
+            [$sample, $target, $maxIndex] = self::processLine($line, $maxIndex);
+            $samples[] = $sample;
+            $targets[] = $target;
+        }
+
+        fclose($handle);
+
+        foreach ($samples as &$sample) {
+            $sample = array_pad($sample, $maxIndex + 1, 0);
+        }
+
+        return [$samples, $targets];
+    }
+
+    private static function openFile(string $filePath)
+    {
+        if (!file_exists($filePath)) {
+            throw FileException::missingFile(basename($filePath));
+        }
+
+        $handle = fopen($filePath, 'rb');
+        if ($handle === false) {
+            throw FileException::cantOpenFile(basename($filePath));
+        }
+
+        return $handle;
+    }
+
+    private static function processLine(string $line, int $maxIndex): array
+    {
+        $columns = self::parseLine($line);
+
+        $target = self::parseTargetColumn($columns[0]);
+        $sample = array_fill(0, $maxIndex + 1, 0);
+
+        $n = count($columns);
+        for ($i = 1; $i < $n; ++$i) {
+            [$index, $value] = self::parseFeatureColumn($columns[$i]);
+            if ($index > $maxIndex) {
+                $maxIndex = $index;
+                $sample = array_pad($sample, $maxIndex + 1, 0);
+            }
+
+            $sample[$index] = $value;
+        }
+
+        return [$sample, $target, $maxIndex];
+    }
+
+    private static function parseLine(string $line): array
+    {
+        $line = explode('#', $line, 2)[0];
+        $line = rtrim($line);
+        $line = str_replace("\t", ' ', $line);
+
+        $columns = explode(' ', $line);
+
+        return $columns;
+    }
+
+    private static function parseTargetColumn(string $column): float
+    {
+        if (!is_numeric($column)) {
+            throw DatasetException::invalidTarget($column);
+        }
+
+        return (float) $column;
+    }
+
+    private static function parseFeatureColumn(string $column): array
+    {
+        $feature = explode(':', $column, 2);
+        if (count($feature) != 2) {
+            throw DatasetException::invalidValue($column);
+        }
+
+        $index = self::parseFeatureIndex($feature[0]);
+        $value = self::parseFeatureValue($feature[1]);
+
+        return [$index, $value];
+    }
+
+    private static function parseFeatureIndex(string $index): int
+    {
+        if (!is_numeric($index) || !ctype_digit($index)) {
+            throw DatasetException::invalidIndex($index);
+        }
+
+        if ((int) $index < 1) {
+            throw DatasetException::invalidIndex($index);
+        }
+
+        return (int) $index - 1;
+    }
+
+    private static function parseFeatureValue(string $value): float
+    {
+        if (!is_numeric($value)) {
+            throw DatasetException::invalidValue($value);
+        }
+
+        return (float) $value;
+    }
+}

src/Exception/DatasetException.php

@@ -12,4 +12,19 @@ public static function missingFolder(string $path): self
     {
         return new self(sprintf('Dataset root folder "%s" missing.', $path));
     }
+
+    public static function invalidTarget(string $target): self
+    {
+        return new self(sprintf('Invalid target "%s".', $target));
+    }
+
+    public static function invalidIndex(string $index): self
+    {
+        return new self(sprintf('Invalid index "%s".', $index));
+    }
+
+    public static function invalidValue(string $value): self
+    {
+        return new self(sprintf('Invalid value "%s".', $value));
+    }
 }

tests/Dataset/Resources/svm/1x1.svm

@@ -0,0 +1 @@
+0 1:2.3

tests/Dataset/Resources/svm/3x1.svm

@@ -0,0 +1,3 @@
+1 1:2.3
+0 1:4.56
+1 1:78.9

tests/Dataset/Resources/svm/3x4.svm

@@ -0,0 +1,3 @@
+1 1:2 2:4 3:6 4:8
+2 1:3 2:5 3:7 4:9
+0 1:1.2 2:3.4 3:5.6 4:7.8

tests/Dataset/Resources/svm/comments.svm

@@ -0,0 +1,2 @@
+0 1:2 # This is a comment.
+1 1:34 # This # is # : # also # a # comment # .

tests/Dataset/Resources/svm/err_empty_line.svm

@@ -0,0 +1,3 @@
+1 1:2.3
+
+0 1:4.56

tests/Dataset/Resources/svm/err_index_zero.svm

@@ -0,0 +1 @@
+0 0:2.3

tests/Dataset/Resources/svm/err_invalid_feature.svm

@@ -0,0 +1 @@
+0 12345

tests/Dataset/Resources/svm/err_invalid_spaces.svm

@@ -0,0 +1 @@
+ 0 1:2.3

tests/Dataset/Resources/svm/err_invalid_value.svm

@@ -0,0 +1 @@
+0 1:xyz

tests/Dataset/Resources/svm/err_no_labels.svm

@@ -0,0 +1 @@
+1:2.3

tests/Dataset/Resources/svm/err_string_index.svm

@@ -0,0 +1 @@
+0 x:2.3

tests/Dataset/Resources/svm/err_string_labels.svm

@@ -0,0 +1 @@
+A 1:2.3

tests/Dataset/Resources/svm/sparse.svm

@@ -0,0 +1,2 @@
+0 2:3.45
+1 5:6.789

tests/Dataset/Resources/svm/tabs.svm

@@ -0,0 +1 @@
+1	1:23	2:45	# comments