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copied!<p>First <code>explode()</code> the array with the delimiter <code>*</code></p> <p>You could then use preg_match_all to match each item in the exploded array. Something like this works with your example input.</p> <pre><code>$layout = explode('*', $input); $columns = array(); foreach ( $layout as $item ){ $parts = array(); //matches either a -, x or + followed by one or more digits preg_match_all('/([+-x])(\d+)/', $item, $matches, PREG_SET_ORDER); foreach ( $matches as $match){ //match[1] hold the + or -, match[2] holds the digits $parts[] = array($match[1], $match[2]); } $columns[] = $parts; } </code></pre> <p>The output from your example ends up like this:</p> <pre><code>array( array( array('+', '2'), array('-', '1'), array('+', '18') ), array( array('+', '7'), array('-', '21'), array('+', '3') ), //etc ); </code></pre> <hr> <p>With PHP 5.3 you could use something like this (untested). The main difference is that the inner loop has been replaced by <a href="http://php.net/manual/en/function.array-map.php" rel="nofollow noreferrer"><code>array_map</code></a> which removes the need for a lot of lines of code. (Array map applies a function to every item in an array and returns the transformed array). PHP 5.3 is required for the nice <a href="http://php.net/manual/en/functions.anonymous.php" rel="nofollow noreferrer">closure syntax</a></p> <pre><code>$layout = explode('*', $input); $columns = array(); foreach ( $layout as $item ){ preg_match_all('/([+-x])(\d+)/', $item, $matches, PREG_SET_ORDER); $columns[] = array_map( function($a){ return array($a[1], $a[2]); }, $matches); } </code></pre> <p>You could also remove the loops altogether:</p> <pre><code>$innerMatch = function($item){ preg_match_all('/([+-x])(\d+)/', $item, $matches, PREG_SET_ORDER); return array_map( function($a){ return array($a[1], $a[2]); }, $matches); }; $columns = array_map($innerMatch, explode('*', $input)); </code></pre> <p>However this has the large disadvantage of not being very readable to most PHP developers which is why I wouldn't recommend using it.</p> <hr> <h3>More explanation</h3> <p>At the request of <a href="https://stackoverflow.com/users/118989/christopher-altman">@Christopher Altman</a></p> <p>The only new bit in the PHP 5.3 version is really this:</p> <pre><code>array_map( function($a){ return array($a[1], $a[2]); }, $matches ); </code></pre> <p>Expanding and altering it a bit (as an example)</p> <pre><code>//bind an anonymous function to the variable $func $func = function($a){ return $a*$a; }; //$func() now calls the anonymous function we have just defined //then we can call it like so: $result = array_map($func, $myArray); </code></pre> <p>So if <code>$myArray</code> is defined as</p> <pre><code>array(1,2,3,4); </code></pre> <p>When it is run through the array map function you can think of it as converting it into</p> <pre><code>array(func(1),func(2),func(3),func(4)); </code></pre> <p>But as PHP isn't a <a href="http://en.wikipedia.org/wiki/Lazy_evaluation" rel="nofollow noreferrer">lazy language</a>, all the functions are evaluated as soon as they are encountered, so the array is returned from array_map as:</p> <pre><code>array(2, 4, 9, 16) </code></pre> <p>In the actual code, <code>preg_match_all</code> returns an array of matches (where the matches are arrays). So all I do is take the array and on every match apply a function that converts the match into a different array in the required format.</p>

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