class-constrained-array-rounding.php
109 lines
| 1 | <?php // phpcs:ignore WordPress.Files.FileName.InvalidClassFileName |
| 2 | |
| 3 | /** |
| 4 | * Lets you round the numeric elements of an array to integers while preserving their sum. |
| 5 | * |
| 6 | * Usage: |
| 7 | * |
| 8 | * Jetpack_Constrained_Array_Rounding::get_rounded_constrained_array( $bound_array ) |
| 9 | * if a specific sum doesn't need to be specified for the bound array |
| 10 | * |
| 11 | * Jetpack_Constrained_Array_Rounding::get_rounded_constrained_array( $bound_array, $sum ) |
| 12 | * If the sum of $bound_array must equal $sum after rounding. |
| 13 | * |
| 14 | * If $sum is less than the sum of the floor of the elements of the array, the class defaults to using the sum of the array elements. |
| 15 | */ |
| 16 | class Jetpack_Constrained_Array_Rounding { |
| 17 | /** |
| 18 | * Get the rounded constrained array. |
| 19 | * |
| 20 | * @param array $bound_array - the array we're rounding. |
| 21 | * @param int $sum - the sum of the array. |
| 22 | * |
| 23 | * @return array |
| 24 | */ |
| 25 | public static function get_rounded_constrained_array( $bound_array, $sum = false ) { |
| 26 | // Convert associative arrays before working with them and convert them back before returning the values |
| 27 | $keys = array_keys( $bound_array ); |
| 28 | $bound_array = array_values( $bound_array ); |
| 29 | |
| 30 | $bound_array_int = self::get_int_floor_array( $bound_array ); |
| 31 | |
| 32 | $lower_sum = array_sum( wp_list_pluck( $bound_array_int, 'floor' ) ); |
| 33 | if ( ! $sum || ( $sum < $lower_sum ) ) { |
| 34 | // If value of sum is not supplied or is invalid, calculate the sum that the returned array is constrained to match |
| 35 | $sum = array_sum( $bound_array ); |
| 36 | } |
| 37 | $diff_sum = $sum - $lower_sum; |
| 38 | |
| 39 | self::adjust_constrained_array( $bound_array_int, $diff_sum ); |
| 40 | |
| 41 | $bound_array_fin = wp_list_pluck( $bound_array_int, 'floor' ); |
| 42 | return array_combine( $keys, $bound_array_fin ); |
| 43 | } |
| 44 | |
| 45 | /** |
| 46 | * Get int floor of array values. |
| 47 | * |
| 48 | * @param array $bound_array - the array we're getting floor values for. |
| 49 | * |
| 50 | * @return array |
| 51 | */ |
| 52 | private static function get_int_floor_array( $bound_array ) { |
| 53 | $bound_array_int_floor = array(); |
| 54 | foreach ( $bound_array as $i => $value ) { |
| 55 | $bound_array_int_floor[ $i ] = array( |
| 56 | 'floor' => (int) floor( $value ), |
| 57 | 'fraction' => $value - floor( $value ), |
| 58 | 'index' => $i, |
| 59 | ); |
| 60 | } |
| 61 | |
| 62 | return $bound_array_int_floor; |
| 63 | } |
| 64 | |
| 65 | /** |
| 66 | * Adjust the constrained array. |
| 67 | * |
| 68 | * @param array $bound_array_int - the array we're adjusting. |
| 69 | * @param int $adjustment - how much we're adjusting the array. |
| 70 | */ |
| 71 | private static function adjust_constrained_array( &$bound_array_int, $adjustment ) { |
| 72 | usort( $bound_array_int, array( self::class, 'cmp_desc_fraction' ) ); |
| 73 | |
| 74 | $start = 0; |
| 75 | $end = $adjustment - 1; |
| 76 | $length = count( $bound_array_int ); |
| 77 | |
| 78 | for ( $i = $start; $i <= $end; $i++ ) { |
| 79 | ++$bound_array_int[ $i % $length ]['floor']; |
| 80 | } |
| 81 | |
| 82 | usort( $bound_array_int, array( self::class, 'cmp_asc_index' ) ); |
| 83 | } |
| 84 | |
| 85 | /** |
| 86 | * Compare fraction values of two arrays. |
| 87 | * |
| 88 | * @param array $a - the first array we're comparing. |
| 89 | * @param array $b - the second array we're comparing. |
| 90 | * |
| 91 | * @return int |
| 92 | */ |
| 93 | private static function cmp_desc_fraction( $a, $b ) { |
| 94 | return $b['fraction'] <=> $a['fraction']; |
| 95 | } |
| 96 | |
| 97 | /** |
| 98 | * Compare index values of two arrays. |
| 99 | * |
| 100 | * @param array $a - the first array. |
| 101 | * @param array $b - the second array. |
| 102 | * |
| 103 | * @return int |
| 104 | */ |
| 105 | private static function cmp_asc_index( $a, $b ) { |
| 106 | return $a['index'] <=> $b['index']; |
| 107 | } |
| 108 | } |
| 109 |