Parsing multiple XML feeds with PHP into one sorted array

Question

I want to create a sortable list that looks something like

• $VAR1[0], $VAR2[0]...
• $VAR1[1], $VAR2[1]...

The data comes from multiple same structured xml files:

$xmlfile="
<Level1>
 <Level2>
  <Level2Item VAR1="1" VAR2="2" ... />
  <Level2Item VAR1="4" VAR2="5" ... />
  <Level2Item VAR1="7" VAR2="8" ... />
 </Level2>
</Level1>";

//Extract each item
$xml = new SimpleXMLElement($xmlfile);
foreach ($xml->Level2[0] as $result) {
 array_push($VAR1Array, $result['VAR1']);
 array_push($VAR2Array, $result['VAR2']);
 //... etc etc
}
//sort
//$sortedArray = sort($VAR1Array);

Output

Array(
  [0] => SimpleXMLElement Object([0] => 1)
  [1] => SimpleXMLElement Object([0] => 4)
  [2] => SimpleXMLElement Object([0] => 7)
)

From this XML structure, what's the best way of storing the data in one array? I want to be able to gather all the data in one array so I can sort it by one or 2 VARs and display the results.

Answer 1

I'm not quite sure what kind of sorting you're trying to do (you should specify with some examples). But optimally, you wouldn't be loading XML fragments into your array.

$xmlfile="
<Level1>
 <Level2>
  <Level2Item VAR1="1" VAR2="2" ... />
  <Level2Item VAR1="4" VAR2="5" ... />
  <Level2Item VAR1="7" VAR2="8" ... />
 </Level2>
</Level1>";

//Extract each item
$xml = new SimpleXMLElement($xmlfile);
foreach ($xml->Level2[0] as $result) {
 $VAR1Array[] = (int) $result['VAR1'];
 $VAR2Array[] = (int) $result['VAR2'];
 //... etc etc
}

Last, sort() works by reference, so don't equate it to a variable (ie just say sort($array); as the entire line, and then $array will be sorted. If you cast as int s like I do in the above example you can use php's default sort function without using a user-defined comparison function like others suggested. And array_push is a little bit slower and harder to read than using php's $var[] syntax to add a new element to an array.

Answer 2

Also, I'm fully sure that you can't assign $xmlfile that way (making unescaped double quotes inside double quotes.

In this code, the best way to define $xmlfile would be:

$xmlfile = <<<XML
<Level1>
 <Level2>
  <Level2Item VAR1="1" VAR2="2" ... />
  <Level2Item VAR1="4" VAR2="5" ... />
  <Level2Item VAR1="7" VAR2="8" ... />
 </Level2>
</Level1>
XML;

or

$xmlfile = '
<Level1>
 <Level2>
  <Level2Item VAR1="1" VAR2="2" ... />
  <Level2Item VAR1="4" VAR2="5" ... />
  <Level2Item VAR1="7" VAR2="8" ... />
 </Level2>
</Level1>';

Answer 3

If I were you, I'd just push all of the SimpleXMLElements onto an array and then use uasort() with a custom callback function to sort as you desire. Does that work?

Answer 4

$xml = simplexml_load_file(...);

$table = array();
foreach ($xml->Level2[0] as $result)
    $table[] = $result->attributes();

function cmp_row($a, $b, $sortColumn)
{
    if ($a == $b)
        return 0;

    return ($a < $b) ? -1 : 1;
}

$sortColumn = 'VAR1'; // make sure it's a clean string

uasort($table, create_function('$a,$b', 'return cmp_row($a, $b, "'.$sortColumn.'")'));

You can also keep the SimpleXMLElements and sort them directly, if you want, like apinstein said.