Initial commit

plugins/jetpack/modules/tiled-gallery/math/class-constrained-array-rounding.php

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