76 lines
2.4 KiB
PHP
76 lines
2.4 KiB
PHP
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<?php
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/**
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* Lets you round the numeric elements of an array to integers while preserving their sum.
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*
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* Usage:
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*
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* Jetpack_Constrained_Array_Rounding::get_rounded_constrained_array( $bound_array )
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* if a specific sum doesn't need to be specified for the bound array
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*
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* Jetpack_Constrained_Array_Rounding::get_rounded_constrained_array( $bound_array, $sum )
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* If the sum of $bound_array must equal $sum after rounding.
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*
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* 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.
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*/
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class Jetpack_Constrained_Array_Rounding {
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public static function get_rounded_constrained_array( $bound_array, $sum = false ) {
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// Convert associative arrays before working with them and convert them back before returning the values
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$keys = array_keys( $bound_array );
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$bound_array = array_values( $bound_array );
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$bound_array_int = self::get_int_floor_array( $bound_array );
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$lower_sum = array_sum( wp_list_pluck( $bound_array_int, 'floor' ) );
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if ( ! $sum || ( $sum < $lower_sum ) ) {
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// If value of sum is not supplied or is invalid, calculate the sum that the returned array is constrained to match
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$sum = array_sum( $bound_array );
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}
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$diff_sum = $sum - $lower_sum;
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self::adjust_constrained_array( $bound_array_int, $diff_sum );
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$bound_array_fin = wp_list_pluck( $bound_array_int, 'floor' );
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return array_combine( $keys, $bound_array_fin );
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}
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private static function get_int_floor_array( $bound_array ) {
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$bound_array_int_floor = array();
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foreach ( $bound_array as $i => $value ){
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$bound_array_int_floor[$i] = array(
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'floor' => (int) floor( $value ),
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'fraction' => $value - floor( $value ),
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'index' => $i,
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);
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}
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return $bound_array_int_floor;
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}
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private static function adjust_constrained_array( &$bound_array_int, $adjustment ) {
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usort( $bound_array_int, array( 'self', 'cmp_desc_fraction' ) );
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$start = 0;
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$end = $adjustment - 1;
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$length = count( $bound_array_int );
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for ( $i = $start; $i <= $end; $i++ ) {
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$bound_array_int[ $i % $length ]['floor']++;
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}
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usort( $bound_array_int, array( 'self', 'cmp_asc_index' ) );
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}
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private static function cmp_desc_fraction( $a, $b ) {
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if ( $a['fraction'] == $b['fraction'] )
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return 0;
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return $a['fraction'] > $b['fraction'] ? -1 : 1;
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}
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private static function cmp_asc_index( $a, $b ) {
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if ( $a['index'] == $b['index'] )
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return 0;
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return $a['index'] < $b['index'] ? -1 : 1;
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}
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}
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