Re-naming and moving

.github/contributing.md

@@ -0,0 +1 @@
+A developer and contribution documentation can be found at https://orange-management.gitbooks.io/developer-guide/content/index.html.

Math/Statistic/Correlation.php

@@ -0,0 +1,119 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.0
+ *
+ * @category   TBD
+ * @package    TBD
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @copyright  2013 Dennis Eichhorn
+ * @license    OMS License 1.0
+ * @version    1.0.0
+ * @link       http://orange-management.com
+ */
+
+namespace phpOMS\Math\Statistic;
+
+/**
+ * Correlation.
+ *
+ * @category   Framework
+ * @package    phpOMS\DataStorage\Database
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @license    OMS License 1.0
+ * @link       http://orange-management.com
+ * @since      1.0.0
+ */
+class Correlation
+{
+
+    /**
+     * Calculage bravais person correlation coefficient.
+     *
+     * Example: ([4, 5, 9, 1, 3], [4, 5, 9, 1, 3])
+     *
+     * @param array $x Values
+     * @param array $y Values
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function bravaisPersonCorrelationCoefficient(array $x, array $y) : float
+    {
+        return MeasureOfDispersion::empiricalCovariance($x, $y) / (MeasureOfDispersion::standardDeviation($x) * MeasureOfDispersion::standardDeviation($y));
+    }
+
+    /**
+     * Get the autocorrelation coefficient (ACF).
+     *
+     * @param array $x Dataset
+     * @param int   $k k-th coefficient
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function autocorrelationCoefficient(array $x, int $k = 0) : float
+    {
+        $squaredMeanDeviation = MeasureOfDispersion::squaredMeanDeviation($x);
+        $mean                 = Average::arithmeticMean($x);
+        $count                = count($x);
+        $sum                  = 0.0;
+
+        for ($i = $k + 1; $i < $count; $i++) {
+            $sum += ($x[$i] - $mean) * ($x[$i - $k] - $mean);
+        }
+
+        return $sum / ($squaredMeanDeviation * count($x));
+    }
+
+    /**
+     * Box Pierce test (portmanteau test).
+     *
+     * @param array $autocorrelations Autocorrelations
+     * @param int   $h                Maximum leg considered
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function boxPierceTest(array $autocorrelations, int $h) : float
+    {
+        $sum = 0;
+        for ($i = 0; $i < $h; $i++) {
+            $sum += $autocorrelations[$i] ** 2;
+        }
+
+        return count($autocorrelations) * $sum;
+    }
+
+    /**
+     * Box Pierce test (portmanteau test).
+     *
+     * @param array $autocorrelations Autocorrelations
+     * @param int   $h                Maximum leg considered
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function ljungBoxTest(array $autocorrelations, int $h) : float
+    {
+        $count = count($autocorrelations);
+        $sum   = 0;
+
+        for ($i = 0; $i < $h; $i++) {
+            $sum += 1 / ($count - $i) * $autocorrelations[$i] ** 2;
+        }
+
+        return $count * ($count + 2) * $sum;
+    }
+}

Math/Statistic/Forecast/Error.php

@@ -14,7 +14,7 @@
  * @link       http://orange-management.com
  */
 
-namespace phpOMS\Math\Forecast;
+namespace phpOMS\Math\Statistic\Forecast;
 
 use phpOMS\Math\Functions;
 use phpOMS\Math\Statistic\Average;

Math/Statistic/Forecast/ForecastIntervalMultiplier.php

@@ -0,0 +1,46 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.0
+ *
+ * @category   TBD
+ * @package    TBD
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @copyright  2013 Dennis Eichhorn
+ * @license    OMS License 1.0
+ * @version    1.0.0
+ * @link       http://orange-management.com
+ */
+namespace phpOMS\Math\Statistic\Forecast;
+use phpOMS\Datatypes\Enum;
+
+/**
+ * Address type enum.
+ *
+ * @category   Framework
+ * @package    phpOMS\Datatypes
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @license    OMS License 1.0
+ * @link       http://orange-management.com
+ * @since      1.0.0
+ */
+abstract class ForecastIntervalMultiplier extends Enum
+{
+    const P_50 = 0.67;
+    const P_55 = 0.76;
+    const P_60 = 0.84;
+    const P_65 = 0.93;
+    const P_70 = 1.04;
+    const P_75 = 1.15;
+    const P_80 = 1.28;
+    const P_85 = 1.44;
+    const P_90 = 1.64;
+    const P_95 = 1.96;
+    const P_96 = 2.05;
+    const P_97 = 2.17;
+    const P_98 = 2.33;
+    const P_99 = 2.58;
+}

Math/Statistic/Forecast/Forecasts.php

@@ -0,0 +1,48 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.0
+ *
+ * @category   TBD
+ * @package    TBD
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @copyright  2013 Dennis Eichhorn
+ * @license    OMS License 1.0
+ * @version    1.0.0
+ * @link       http://orange-management.com
+ */
+namespace phpOMS\Math\Statistic\Forecast;
+
+/**
+ * Address type enum.
+ *
+ * @category   Framework
+ * @package    phpOMS\Datatypes
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @license    OMS License 1.0
+ * @link       http://orange-management.com
+ * @since      1.0.0
+ */
+class Forecast
+{
+    /**
+     * Get forecast interval.
+     * 
+     * 
+     *
+     * @param array $observed   Dataset
+     * @param array $forecasted Forecasted
+     *
+     * @return array
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function getForecastInteval(float $forecast, float $standardDeviation, float $interval = ForecastIntervalMultiplier::P_95) : array
+    {
+        return [$forecast - $interval * $standardDeviation, $forecast + $interval * $standardDeviation];
+    }
+}

Math/Statistic/Forecast/LinearRegression.php

@@ -0,0 +1,185 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.0
+ *
+ * @category   TBD
+ * @package    TBD
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @copyright  2013 Dennis Eichhorn
+ * @license    OMS License 1.0
+ * @version    1.0.0
+ * @link       http://orange-management.com
+ */
+
+namespace phpOMS\Math\Forecast\Statistic;
+
+use phpOMS\Math\Statistic\Average;
+use phpOMS\Math\Statistic\Forecast\ForecastIntervalMultiplier;
+use phpOMS\Math\Statistic\MeasureOfDispersion;
+
+/**
+ * Regression class.
+ *
+ * @category   Framework
+ * @package    phpOMS\DataStorage\Database
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @license    OMS License 1.0
+ * @link       http://orange-management.com
+ * @since      1.0.0
+ */
+class LinearRegression
+{
+    /**
+     * Get linear regression based on scatter plot.
+     *
+     * y = b0 + b1 * x
+     *
+     * @param array $x Obersved x values
+     * @param array $y Observed y values
+     *
+     * @return array [b0 => ?, b1 => ?]
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function getLinearRegresseion(array $x, array $y) : array
+    {
+        $b1 = self::getBeta1($x, $y);
+
+        return ['b0' => self::getBeta0($x, $y, $b1), 'b1' => $b1];
+    }
+
+    /**
+     * Get linear regression parameter beta 1.
+     *
+     * @param array $x Obersved x values
+     * @param array $y Observed y values
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    private static function getBeta1(array $x, array $y) : float
+    {
+        $count = count($x);
+        $meanX = Average::arithmeticMean($x);
+        $meanY = Average::arithmeticMean($y);
+
+        $sum1 = 0;
+        $sum2 = 0;
+
+        for ($i = 0; $i < $count; $i++) {
+            $sum1 += ($y[$i] - $meanY) * ($x[$i] - $meanX);
+            $sum2 += ($x[$i] - $meanX) ** 2;
+        }
+
+        return $sum1 / $sum2;
+    }
+
+    /**
+     * Get linear regression parameter beta 0.
+     *
+     * @param array $x  Obersved x values
+     * @param array $y  Observed y values
+     * @param float $b1 Beta 1
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    private static function getBeta0(array $x, array $y, float $b1) : float
+    {
+        return Average::arithmeticMean($y) - $b1 * Average::arithmeticMean($x);
+    }
+
+    /**
+     * Goodness of fit.
+     *
+     * Evaluating how well the observed data fit the linear regression model
+     *
+     * @param array $observed   Obersved y values
+     * @param array $forecasted Forecasted y values
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function getGoodnessOfFit(array $observed, array $forecasted) : float
+    {
+        $countO = count($observed);
+        $countF = count($forecasted);
+        $sum1   = 0;
+        $sum2   = 0;
+        $meanY  = Average::arithmeticMean($observed);
+
+        for ($i = 0; $i < $countF; $i++) {
+            $sum1 += ($forecasted[$i] - $meanY) ** 2;
+        }
+
+        for ($i = 0; $i < $countO; $i++) {
+            $sum2 += ($observed[$i] - $meanY) ** 2;
+        }
+
+        return $sum1 / $sum2;
+    }
+
+    /**
+     * Standard error of the regression.
+     *
+     * Used in order to evaluate the performance of the linear regression
+     *
+     * @param array $errors Errors (e = y - y_forecasted)
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function getStandardErrorOfRegression(array $errors) : float
+    {
+        $count = count($errors);
+        $sum   = 0.0;
+
+        for ($i = 0; $i < $count; $i++) {
+            $sum += $errors[$i] ** 2;
+        }
+
+        // todo: could this be - 1 depending on the different definitions?!
+        return sqrt(1 / ($count - 2) * $sum);
+    }
+
+    /**
+     * Get predictional interval for linear regression.
+     *
+     * @param float $forecasted Forecasted y value
+     * @param array $x          observex x values
+     * @param array $errors     Errors for y values (y - y_forecasted)
+     * @param float $multiplier Multiplier for interval
+     *
+     * @return array
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function getPredictionInterval(float $forecasted, array $x, array $errors, float $multiplier = ForecastIntervalMultiplier::P_95) : array
+    {
+        $count = count($x);
+        $meanX = Average::arithmeticMean($x);
+        $sum   = 0.0;
+
+        for ($i = 0; $i < $count; $i++) {
+            $sum += ($x[$i] - $meanX) ** 2;
+        }
+
+        $interval = $multiplier * self::getStandardErrorOfRegression($errors) * sqrt(1 + 1 / $count + $sum / (($count - 1) * MeasureOfDispersion::standardDeviation($x) ** 2));
+
+        return [$forecasted - $interval, $forecasted + $interval];
+    }
+}

Math/Statistic/MeasureOfDispersion.php

@@ -189,24 +189,6 @@ class MeasureOfDispersion
         return $sum / ($count - 1);
     }
 
-    /**
-     * Calculage bravais person correlation coefficient.
-     *
-     * Example: ([4, 5, 9, 1, 3], [4, 5, 9, 1, 3])
-     *
-     * @param array $x Values
-     * @param array $y Values
-     *
-     * @return float
-     *
-     * @since  1.0.0
-     * @author Dennis Eichhorn <d.eichhorn@oms.com>
-     */
-    public static function bravaisPersonCorrelationcoefficient(array $x, array $y) : float
-    {
-        return self::empiricalCovariance($x, $y) / (self::standardDeviation($x) * self::standardDeviation($y));
-    }
-
     /**
      * Get interquartile range.
      *
@@ -265,28 +247,4 @@ class MeasureOfDispersion
         return $sum / count($x);
     }
 
-    /**
-     * Get the autocorrelation coefficient (ACF).
-     *
-     * @param array $x Dataset
-     * @param int   $k k-th coefficient
-     *
-     * @return float
-     *
-     * @since  1.0.0
-     * @author Dennis Eichhorn <d.eichhorn@oms.com>
-     */
-    public static function autocorrelationCoefficient(array $x, int $k = 0) : float
-    {
-        $squaredMeanDeviation = self::squaredMeanDeviation($x);
-        $mean                 = Average::arithmeticMean($x);
-        $count                = count($x);
-        $sum                  = 0.0;
-
-        for ($i = $k + 1; $i < $count; $i++) {
-            $sum += ($x[$i] - $mean) * ($x[$i - $k] - $mean);
-        }
-
-        return $sum / ($squaredMeanDeviation * count($x));
-    }
 }

Utils/Compression/LZW.php

@@ -89,11 +89,11 @@ class LZW implements CompressionInterface
             if ($dictionary[$k]) {
                 $entry = $dictionary[$k];
             } else {
-                if ($k === $dictSize) {
-                    $entry = $w . $w[0];
-                } else {
+                if ($k !== $dictSize) {
                     return null;
                 }
+
+                $entry = $w . $w[0];
             }
 
             $result .= $entry;

Utils/Converter/File.php

@@ -54,11 +54,11 @@ class File
         if ($bytes < 1000) {
             return $bytes . 'b';
         } elseif ($bytes > 999 && $bytes < 1000000) {
-            return $bytes / 1000 . 'kb';
+            return ((float) number_format($bytes / 1000, 1)) . 'kb';
         } elseif ($bytes > 999999 && $bytes < 1000000000) {
-            return $bytes / 1000000 . 'mb';
+            return ((float) number_format($bytes / 1000000, 1)) . 'mb';
         } else {
-            return $bytes / 1000000000 . 'gb';
+            return ((float) number_format($bytes / 1000000000, 1)) . 'gb';
         }
     }
 
@@ -75,11 +75,11 @@ class File
     public static function kilobyteSizeToString(int $kilobytes) : string
     {
         if ($kilobytes < 1000) {
-            return round($kilobytes, 2) . 'kb';
+            return ((float) number_format($kilobytes, 1)) . 'kb';
         } elseif ($kilobytes > 999 && $kilobytes < 1000000) {
-            return round($kilobytes / 1000, 2) . 'mb';
+            return ((float) number_format($kilobytes / 1000, 1)) . 'mb';
         } else {
-            return round($kilobytes / 1000000, 2) . 'gb';
+            return ((float) number_format($kilobytes / 1000000, 1)) . 'gb';
         }
     }
 }

Utils/Converter/Measurement.php

@@ -38,11 +38,14 @@ class Measurement
      *
      * @return float
      *
+     * @todo: implement more
+     *
      * @since  1.0.0
      * @author Dennis Eichhorn <d.eichhorn@oms.com>
      */
-    public static function convertTemperature(float $value, string $from, string $to) : float
+    public static function convertTemperature(float $value, string $from = TemperatureType::FAHRENHEIT, string $to = TemperatureType::CELSIUS) : float
     {
+        // to celving
         switch ($from) {
             case TemperatureType::CELSIUS:
                 $value += 273.15;
@@ -77,4 +80,204 @@ class Measurement
 
         return $value;
     }
+
+    /**
+     * Convert weight.
+     *
+     * @param float  $value Value to convert
+     * @param string $from  Input weight
+     * @param string $to    Output weight
+     *
+     * @return float
+     *
+     * @todo: implement more
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function convertWeight(float $value, string $from = WeightType::GRAM, string $to = WeightType::KILOGRAM) : float
+    {
+        // to gram
+        switch ($from) {
+            case WeightType::MILLIGRAM:
+                $value /= 1000;
+                break;
+            case WeightType::GRAM:
+                break;
+            case WeightType::KILOGRAM:
+                $value *= 1000;
+                break;
+            case WeightType::TONS:
+                $value *= 1000000;
+                break;
+            case WeightType::STONES:
+                $value /= 0.15747 * 1000;
+                break;
+            case WeightType::OUNCES:
+                $value /= 0.035274;
+                break;
+            default:
+                throw new \InvalidArgumentException('Weight not supported');
+        }
+
+        switch ($to) {
+            case WeightType::MILLIGRAM:
+                $value *= 1000;
+                break;
+            case WeightType::GRAM:
+                break;
+            case WeightType::KILOGRAM:
+                $value /= 1000;
+                break;
+            case WeightType::TONS:
+                $value /= 1000000;
+                break;
+            case WeightType::STONES:
+                $value *= 0.15747 * 1000;
+                break;
+            case WeightType::OUNCES:
+                $value *= 0.035274;
+                break;
+            default:
+                throw new \InvalidArgumentException('Weight not supported');
+        }
+
+        return $value;
+    }
+
+    /**
+     * Convert length.
+     *
+     * @param float  $value Value to convert
+     * @param string $from  Input weight
+     * @param string $to    Output weight
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function convertLength(float $value, string $from = WeightType::GRAM, string $to = WeightType::KILOGRAM) : float
+    {
+        return $value;
+    }
+
+    /**
+     * Convert area.
+     *
+     * @param float  $value Value to convert
+     * @param string $from  Input weight
+     * @param string $to    Output weight
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function convertArea(float $value, string $from = WeightType::GRAM, string $to = WeightType::KILOGRAM) : float
+    {
+        return $value;
+    }
+
+    /**
+     * Convert volume.
+     *
+     * @param float  $value Value to convert
+     * @param string $from  Input weight
+     * @param string $to    Output weight
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function convertVolume(float $value, string $from = WeightType::GRAM, string $to = WeightType::KILOGRAM) : float
+    {
+        return $value;
+    }
+
+    /**
+     * Convert speed.
+     *
+     * @param float  $value Value to convert
+     * @param string $from  Input weight
+     * @param string $to    Output weight
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function convertSpeed(float $value, string $from = WeightType::GRAM, string $to = WeightType::KILOGRAM) : float
+    {
+        return $value;
+    }
+
+    /**
+     * Convert speed.
+     *
+     * @param float  $value Value to convert
+     * @param string $from  Input weight
+     * @param string $to    Output weight
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function convertTime(float $value, string $from = WeightType::GRAM, string $to = WeightType::KILOGRAM) : float
+    {
+        return $value;
+    }
+
+    /**
+     * Convert speed.
+     *
+     * @param float  $value Value to convert
+     * @param string $from  Input weight
+     * @param string $to    Output weight
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function convertAngle(float $value, string $from = WeightType::GRAM, string $to = WeightType::KILOGRAM) : float
+    {
+        return $value;
+    }
+
+    /**
+     * Convert speed.
+     *
+     * @param float  $value Value to convert
+     * @param string $from  Input weight
+     * @param string $to    Output weight
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function convertPressure(float $value, string $from = WeightType::GRAM, string $to = WeightType::KILOGRAM) : float
+    {
+        return $value;
+    }
+
+    /**
+     * Convert speed.
+     *
+     * @param float  $value Value to convert
+     * @param string $from  Input weight
+     * @param string $to    Output weight
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function convertEnergie(float $value, string $from = WeightType::GRAM, string $to = WeightType::KILOGRAM) : float
+    {
+        return $value;
+    }
 }

Utils/Converter/WeightType.php

@@ -0,0 +1,40 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.0
+ *
+ * @category   TBD
+ * @package    TBD
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @copyright  2013 Dennis Eichhorn
+ * @license    OMS License 1.0
+ * @version    1.0.0
+ * @link       http://orange-management.com
+ */
+namespace phpOMS\Utils\Converter;
+
+use phpOMS\Datatypes\Enum;
+
+/**
+ * Weight type enum.
+ *
+ * @category   Framework
+ * @package    phpOMS\Utils\Converter
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @license    OMS License 1.0
+ * @link       http://orange-management.com
+ * @since      1.0.0
+ */
+abstract class WeightType extends Enum
+{
+    const MILLIGRAM = 'mg';
+    const GRAM = 'g';
+    const KILOGRAM = 'kg';
+    const TONS = 't';
+    const POUNDS = 'lb';
+    const OUNCES = 'oz';
+    const STONES = 'st';
+}

Utils/JsonBuilder.php

@@ -26,7 +26,7 @@ namespace phpOMS\Utils;
  * @link       http://orange-management.com
  * @since      1.0.0
  */
-class JsonBuilder
+class JsonBuilder implements \Serializable
 {
 
     /**
@@ -64,7 +64,7 @@ class JsonBuilder
      * Add data.
      *
      * @param string $path      Path used for storage
-     * @param array  $value     Data to add
+     * @param mixed  $value     Data to add
      * @param bool   $overwrite Should overwrite existing data
      *
      * @return void
@@ -72,7 +72,7 @@ class JsonBuilder
      * @since  1.0.0
      * @author Dennis Eichhorn
      */
-    public function add(string $path, array $value, bool $overwrite = true)
+    public function add(string $path, $value, bool $overwrite = true)
     {
         $this->json = ArrayUtils::setArray($path, $this->json, $value, '/', $overwrite);
     }
@@ -81,28 +81,39 @@ class JsonBuilder
      * Remove data.
      *
      * @param string $path  Path to the element to delete
-     * @param string $delim Delim used inside path
      *
      * @return void
      *
      * @since  1.0.0
      * @author Dennis Eichhorn
      */
-    public function remove(string $path, string $delim)
+    public function remove(string $path)
     {
-        $this->json = ArrayUtils::unsetArray($path, $this->json, $delim);
+        $this->json = ArrayUtils::unsetArray($path, $this->json, '/');
     }
 
     /**
-     * Get json string.
-     *
-     * @return string
-     *
-     * @since  1.0.0
-     * @author Dennis Eichhorn
+     * String representation of object
+     * @link  http://php.net/manual/en/serializable.serialize.php
+     * @return string the string representation of the object or null
+     * @since 5.1.0
      */
-    public function __toString()
+    public function serialize()
     {
         return json_encode($this->json);
     }
+
+    /**
+     * Constructs the object
+     * @link  http://php.net/manual/en/serializable.unserialize.php
+     * @param string $serialized <p>
+     *                           The string representation of the object.
+     *                           </p>
+     * @return void
+     * @since 5.1.0
+     */
+    public function unserialize($serialized)
+    {
+        $this->json = json_decode($serialized);
+    }
 }

Utils/Permutation.php

@@ -108,11 +108,13 @@ class Permutation
     public static function permutate($toPermute, array $key)
     {
         if (!is_array($toPermute) || !is_string($toPermute)) {
-            throw new \Exception();
+            throw new \InvalidArgumentException('Parameter has to be array or string');
         }
 
-        if (count($key) > strlen($toPermute)) {
-            throw new \Exception();
+        $length = is_array($toPermute) ? count($toPermute) : strlen($toPermute);
+
+        if (count($key) > $length) {
+            throw new \InvalidArgumentException('There mustn not be more keys than permutation elements.');
         }
 
         $i = 0;