A "simple" PHP function to convert arrays into DataTable JSON export format fit to use with Google Charts

gistfile1.php

<?php
/**
 * arrayToDataTable()
 * Converts PHP arrays to nested arrays fit for json_encode()
 *
 * Format Notice:
 * - $cols contains all the columns for the DataTable, each column having a type and a label.
 *   Columns can be defined as plain arrays (containing only type and label, see below) or as a named array,
 *   with each of the properties defined as key => value pairs. All columns must have at least a 'type'.
 *
 * - $rows contain the data for the DataTable, each row contained in an array. Similar approach works for $rows as
 *   did for $cols, where values can be defined either as plain values inside the row or as a named array.
 *   Every row must contain the same amount of values (cells) as there are columns, null values are accepted.
 *
 * - This implementation attempts to follow Google's DataTable JSON format as closely as possible.
 *
 * - Example $cols:
 *   $cols = array(
 *     array('type' => 'string', 'label' => 'Time'), 'id' => 'time', // Named Array
 *     array('number', 'Hits'), // Plain Array
 *   );
 *
 * - Example $rows:
 * $rows = array(
 *     array(
 *       '2013-06-28', // Plain Value
 *       array('v' => 7, 'f' => 'Seven', 'p' => array('style' => 'border: 1px solid green;')), // Value as a Named Array
 *     ),
 *   );
 *
 * @see https://developers.google.com/chart/interactive/docs/reference#dataparam
 * @author Diftraku <diftraku(at)derpy(dot)me>
 * @param array $cols
 * @param array $rows
 * @return null
 * @throws IllegalArgumentException
 */
static function arrayToDataTable(array $cols, array $rows) {
	if (!empty($rows) && !empty($cols)) {
		if (count($cols) !== count($rows[0])) {
			// Values specified in the first row of $rows don't add up to the ones in $cols
			throw new IllegalArgumentException('Amount of values in rows must match amount of columns');
		}

		$return = array();

		// Process columns
		foreach ($cols as $column) {
			// Check if the column has a type
			if (!array_key_exists('type', $column) && array_key_exists(0, $column)) {
				// Try to mangle us a type
				switch ($column[0]) {
					case 'boolean':
					case 'number':
					case 'string':
					case 'date':
					case 'datetime':
					case 'timeofday':
						$column['type'] = $column[0];
					break;
					default:
						$column['type'] = 'string';
					break;
				}
				unset($column[0]);
				// Assume the second entry is a label
				if (array_key_exists(1, $column)) {
					$column['label'] = $column[1];
					unset($column[1]);
				}
			}
			// @TODO: Add key => val validation here?
			$return['cols'][] = $column;
		}

		// Process rows
		foreach ($rows as $row) {
			// <3 Nested Arrays
			$tmp = array('c' => array());
			foreach ($row as $key => $cell) {
				// Is our cell a plain or an array with other stuff?
				if (!is_array($cell)) {
					$cell = array('v' => $cell);
				}
				// @TODO: Add key => val validation here?
				$tmp['c'][] = $cell;
			}
			$return['rows'][] = $tmp;
		}

		return $return;
	}
	else {
		// We can't work without something to work on
		throw new IllegalArgumentException('Unable to process empty arrays');
	}
}