Part-DB.Part-DB-server/src/Services/SIFormatter.php

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<?php
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/**
* This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
*
* Copyright (C) 2019 - 2020 Jan Böhmer (https://github.com/jbtronics)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
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declare(strict_types=1);
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/**
* This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
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*
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* Copyright (C) 2019 Jan Böhmer (https://github.com/jbtronics)
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*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
*/
namespace App\Services;
/**
* A service that helps you to format values using the SI prefixes.
*/
class SIFormatter
{
/**
* Returns the magnitude of a value (the count of decimal place of the highest decimal place).
* 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
*/
public function getMagnitude(float $value): int
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{
return (int) floor(log10(abs($value)));
}
/**
* 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"].
*/
public function getPrefixByMagnitude(int $magnitude): array
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{
$prefixes_pos = ['', 'k', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'];
$prefixes_neg = ['', 'm', 'μ', 'n', 'p', 'f', 'a', 'z', 'y'];
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if ($magnitude >= 0) {
$nearest = (int) floor(abs($magnitude) / 3);
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$symbol = $prefixes_pos[$nearest];
} else {
$nearest = (int) round(abs($magnitude) / 3);
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$symbol = $prefixes_neg[$nearest];
}
if ($magnitude < 0) {
$nearest *= -1;
}
return [10 ** (3 * $nearest), $symbol];
}
public function convertValue(float $value): array
{
//Choose the prefix to use
$tmp = $this->getPrefixByMagnitude($this->getMagnitude($value));
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return [
'value' => $value / $tmp[0],
'prefix_magnitude' => log10($tmp[0]),
'prefix' => $tmp[1],
];
}
/**
* Formats the given value to a string, using the given options.
*
* @param float $value The value that should be converted
* @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 The formatted value
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*/
public function format(float $value, string $unit = '', int $decimals = 2): string
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{
[$divisor, $symbol] = $this->getPrefixByMagnitude($this->getMagnitude($value));
$value /= $divisor;
//Build the format string, e.g.: %.2d km
if ('' !== $unit || '' !== $symbol) {
$format_string = '%.'.$decimals.'f '.$symbol.$unit;
} else {
$format_string = '%.'.$decimals.'f';
}
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return sprintf($format_string, $value);
}
}