wordpress: table shortcode

gistfile1

function simple_table( $atts ) {
    extract( shortcode_atts( array(
        'cols' => 'none',
        'data' => 'none',
    ), $atts ) );
    $cols = explode(',',$cols);
    $data = explode('<data>',$data);
    $total = count($cols);
    $output .= '<table class="mytable"><tr class="th">';
    foreach($cols as $col):
        $output .= '<td>'.$col.'</td>';
    endforeach;
    $output .= '</tr><tr>';
    $counter = 1;
    foreach($data as $datum):
        $output .= '<td bgcolor="#f1f1f1">'.$datum.'</td>';
        if($counter%$total==0):
            $output .= '</tr>';
        endif;
        $counter++;
    endforeach;
        $output .= '</table>';
    return $output;
}
add_shortcode( 'table', 'simple_table' );
/*usage [table cols="names,values" data="name1,25,name2,409"] */