如何对逗号分隔值进行分组

Question

I want group the comma separated values in the columns. For example, in the following data, I want to group the first value of each row in a group A, second in group B and so on. The values are random and the purpose is to generate an XML file.

Sample data:

1,2,3,4,5
3,5,4,6,2

Desired output:

<group n="A">
    <col n="V"><col_value>1</col_value></col>
    <col n="V"><col_value>3</col_value></col>
</group>

<group n="B">
    <col n="V"><col_value>2</col_value></col>
    <col n="V"><col_value>5</col_value></col>
</group>

What I'm trying:

I'm trying following code, I'm only unable to figure out how to create a group only once and then put the values in it,

$a_exists = 0;
$b_exists = 0;

if (($handle = fopen("test.csv", "r")) !== FALSE) {
    while (($d = fgetcsv($handle)) !== FALSE) { 

        //create group A
        if ($a_exists != 1){                    
            $xml->startElement('group');
                $xml->writeAttribute('n', 'A');                                 
        }
            $xml->startElement('col');
            $xml->writeAttribute('n', 'V');             
                $xml->writeElement('col_value', $d[0]);
            $xml->endElement();                         

        if ($a_exists != 1){                                
            $xml->endElement();
            $a_exists = 1;
        }

        //repeat above code to generate group B.    

    }
}

Answer 1

What I Would do is group them first, per column, then create the XML. Sample:

// open csv
$fh = fopen('test.csv', 'r');
$data = array();
while(!feof($fh)) {
    $row = fgetcsv($fh); // get each row
    // group them first
    foreach($row as $key => $val) {
        $data[$key][] = $val;
    }
}

$i = 'A';
$xml = new SimpleXMLElement('<groups/>');
foreach($data as $batch) {
    $group = $xml->addChild('group', '');
    $group->addAttribute('n', $i);

    foreach($batch as $value) {
        $col = $group->addChild('cols', ' ');
        $col->addAttribute('n', 'V');
        $col->addChild('col_value', $value);
    }

    $i++; // increment A -> B -> so on..
}

echo $xml->saveXML();