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<?php |
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/** |
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* |
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* part-db version 0.1 |
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* Copyright (C) 2005 Christoph Lechner |
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* http://www.cl-projects.de/ |
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* |
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* part-db version 0.2+ |
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* Copyright (C) 2009 K. Jacobs and others (see authors.php) |
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* http://code.google.com/p/part-db/ |
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* |
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* Part-DB Version 0.4+ |
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* Copyright (C) 2016 - 2019 Jan Böhmer |
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* https://github.com/jbtronics |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public License |
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* as published by the Free Software Foundation; either version 2 |
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* of the License, or (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA |
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* |
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*/ |
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namespace App\Services; |
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/** |
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* A service that helps you to format values using the SI prefixes. |
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* @package App\Services |
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*/ |
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class SIFormatter |
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{ |
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/** |
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* Returns the magnitude of a value (the count of decimal place of the highest decimal place). |
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* For example, for 100 (=10^2) this function returns 2. For -2500 (=-2.5*10^3) this function returns 3. |
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* @param float $value The value of which the magnitude should be determined. |
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* @return int The magnitude of the value |
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*/ |
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public function getMagnitude(float $value) : int |
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{ |
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return (int) floor(log10(abs($value))); |
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} |
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/** |
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* Returns the best SI prefix (and its corresponding divisor) for the given magnitude. |
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* @param int $magnitude The magnitude for which the prefix should be determined. |
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* @return array A array, containing the divisor in first element, and the prefix symbol in second. For example, [1000, "k"]. |
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*/ |
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public function getPrefixByMagnitude(int $magnitude) : array |
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{ |
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$prefixes_pos = ['' ,'k', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y']; |
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$prefixes_neg = ['' ,'m', 'μ', 'n', 'p', 'f', 'a', 'z', 'y']; |
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//Determine nearest prefix index. |
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$nearest = (int) round(abs($magnitude) / 3); |
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if ($magnitude >= 0) { |
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$symbol = $prefixes_pos[$nearest]; |
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} else { |
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$symbol = $prefixes_neg[$nearest]; |
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} |
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if ($magnitude < 0) { |
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$nearest *= -1; |
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} |
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return [10 ** (3 * $nearest), $symbol]; |
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} |
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/** |
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* |
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* @param float $value |
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* @return array |
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*/ |
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public function convertValue(float $value) : array |
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{ |
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//Choose the prefix to use |
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$tmp = $this->getPrefixByMagnitude($this->getMagnitude($value)); |
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$ret = array( |
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'value' => $value / $tmp[0], |
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'prefix_magnitude' => log10($tmp[0]), |
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'prefix' => $tmp[1] |
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); |
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return $ret; |
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} |
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/** |
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* Formats the given value to a string, using the given options |
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* @param float $value The value that should be converted |
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* @param string $unit The unit that should be appended after the prefix |
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* @param int $decimals The number of decimals (after decimal dot) that should be outputed. |
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* @return string |
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*/ |
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public function format(float $value, string $unit = '', int $decimals = 2) : string |
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{ |
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[$divisor, $symbol] = $this->getPrefixByMagnitude($this->getMagnitude($value)); |
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$value /= $divisor; |
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//Build the format string, e.g.: %.2d km |
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$format_string = '%.' . $decimals . 'f ' . $symbol . $unit; |
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return sprintf($format_string, $value); |
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} |
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} |