Sorting and grouping SimpleXML Data

Question

I am sorting & grouping publication data from an XML file. The methods I am currently using are working fine for the most part, although I feel like there is a more efficient way to do what I am trying to accomplish.

Here is a sample of what the target nodes look like:

<comic>
      <id>117</id>
      <mainsection>
        <series>
          <displayname>My Amazing Adventure</displayname>
          <sortname>My Amazing Adventure</sortname>
        </series>
      </mainsection>
      <issuenr>2</issuenr>
      <seriefirstletter>
        <displayname>M</displayname>
        <sortname>M</sortname>
      </seriefirstletter>
    </comic>

Here are the current steps I am taking.

• Loading the XML file with SimpleXML
• Specifying the target node and using iterator_to_array to convert it to an array
• Using a usort function that compares (strcmp) the seriesname attribute, to sort all of the series alphabetically.
• I'm using a query string for each page to specify each letter of the alphabet and using an IF statement that compares the query string letter to the seriesfirstletter value. So only the applicable nodes are returned.
• I then begin my foreach statement. Echoing out the data I want, into LI items.
• Finally, I'm using jQuery to look at the ID's for each LI item and visually group them. I've created a PHP variable that uses the seriesname, with the spaces removed, for the ID's. It inserts a H4 heading with the proper series name, above the group and inserts a separating DIV below the group.

While the alphabetical sorting is working properly. I'm also wanting the issues within the same series to be sorted numerically. This is not currently working. Right now, the numeric sort order looks something like this: 1, 10, 12, 2, 3.

I would like to get the numerical sorting issue straightened out. I also feel like the grouping that I'm currently doing in jQuery, could be done in PHP, while I'm going through the loop. Any advice on a better / more efficient way to handle this data, would be greatly appreciated.

Answer 1

Let's say you've got all <comic> elements as an iterator already. First of all convert it to an array so we can use the array functions:

$comics = iterator_to_array($comics, 0);

Then you want to sort this array based on some value, here the value of the <issuenr> child. This can be done with usort and the help of a callback function:

$success = usort($comics, function($a, $b) {
    return strnatcmp($a->issuenr, $b->issuenr);
});

The callback function just picks the concrete values you want to compare with each other and passes it along to strnatcmp which is the natural order comparison I commented above.

---

The following code-example shows how to list all series that match a specific search letter, natsorted and distinct (no duplicate names, grouped).

The search and the grouping is both done with an xpath query:

$searchval = 'T';

$file = 'compress.zlib://comiclist10-12.xml.gz';

$xml = simplexml_load_file($file);

$series = $xml->xpath(
    "/*/comiclist/comic[./seriefirstletter/displayname = '$searchval']
        /mainsection/series/sortname[
            not(. = ../../../following-sibling::comic/mainsection/series/sortname)
        ]"
);

natsort($series);

foreach($series as $serie)
{
    echo $serie, "\n";
}

This will then output the sorted list:

Tale of the Batman: Gotham by Gaslight, A
Tales of Suspense: Captain America & Iron Man #1 Commemorative Edition
Tales to Astonish, Vol. 1
Teenage Mutant Ninja Turtles
Teenage Mutant Ninja Turtles Micro Series
Teenage Mutant Ninja Turtles Ongoing
Terminator / Robocop: Kill Human
Thanos
Thing, Vol. 1
Thor, Vol. 2
Thor, Vol. 3
Thor: Blood Oath
Thor: For Asgard
Thor: Man of War
Thor: Son of Asgard
Thor Annual
Thor Corps
Thundercats
Thundercats (DC Comics - Wildstorm)
Thundercats: Enemy's Pride
Tomb of Dracula, Vol. 4, The
Torch, The
Toxin
Transformers: Armada
Transformers: Generation One
Transformers: Infiltration
Truth: Red, White & Black

In the next step you want to list all comics in that series, that would be an inner foreach:

foreach ($series as $serie) {
    echo $serie, "\n";

    $string = xpath_string($serie);

    $comics = $serie->xpath("../../../../comic[./mainsection/series/sortname = $string]");

    foreach ($comics as $i => $comic) {
        printf(" %d. id: %s\n", $i+1, $comic->id);
    }
}

Which will then fetch the comics for each series, output:

Tale of the Batman: Gotham by Gaslight, A
 1. id: 8832
Tales of Suspense: Captain America & Iron Man #1 Commemorative Edition
 1. id: 3591
Tales to Astonish, Vol. 1
 1. id: 3589
Teenage Mutant Ninja Turtles
 1. id: 117
Teenage Mutant Ninja Turtles Micro Series
 1. id: 13789
Teenage Mutant Ninja Turtles Ongoing
 1. id: 13780
 2. id: 13782
 3. id: 13787
Terminator / Robocop: Kill Human
 1. id: 13775
Thanos
 1. id: 3597
Thing, Vol. 1
 1. id: 3746
Thor, Vol. 2
 1. id: 5873
Thor, Vol. 3
 1. id: 1035
 2. id: 1635
 3. id: 2318
 4. id: 2430
 5. id: 2463
 6. id: 3333
 7. id: 3616
 8. id: 11731
 9. id: 11733
Thor: Blood Oath
 1. id: 3635
 2. id: 3636
Thor: For Asgard
 1. id: 11545
 2. id: 11546
Thor: Man of War
 1. id: 3644
Thor: Son of Asgard
 1. id: 538
 2. id: 3645
Thor Annual
 1. id: 5868
Thor Corps
 1. id: 3640
Thundercats
 1. id: 209
Thundercats (DC Comics - Wildstorm)
 1. id: 3654
Thundercats: Enemy's Pride
 1. id: 3649
Tomb of Dracula, Vol. 4, The
 1. id: 3719
Torch, The
 1. id: 2328
 2. id: 2330
 3. id: 2461
Toxin
 1. id: 3720
Transformers: Armada
 1. id: 3737
Transformers: Generation One
 1. id: 557
Transformers: Infiltration
 1. id: 3729
 2. id: 3731
Truth: Red, White & Black
 1. id: 3750
 2. id: 3751

The code of the xpath_string function can be found in another answer of mine.

Answer 2

You can use

$key = "id" ;
$iterator = new SimpleXMLIterator($xml);
$array = json_decode(json_encode($iterator), TRUE);
__xsort($array['comic'],"id") ;
var_dump($array['comic']);

Output

array
  0 => 
    array
      'id' => string '1' (length=1)
      'mainsection' => 
        array
          'series' => 
            array
              ...
  1 => 
    array
      'id' => string '2' (length=1)
      'mainsection' => 
        array
          'series' => 
            array
              ...
  2 => 
    array
      'id' => string '3' (length=1)
      'mainsection' => 
        array
          'series' => 
            array
              ...
  3 => 
    array
      'id' => string '10' (length=2)
      'mainsection' => 
        array
          'series' => 
            array
              ...
  4 => 
    array
      'id' => string '12' (length=2)
      'mainsection' => 
        array
          'series' => 
            array
              ... 

XML USed

$xml = "<comics>
<comic>
      <id>1</id>
      <mainsection>
        <series>
          <displayname>My Amazing Adventure - 1</displayname>
          <sortname>My Amazing Adventure</sortname>
        </series>
      </mainsection>
    </comic>

<comic>
      <id>10</id>
      <mainsection>
        <series>
          <displayname>My Amazing Adventure - 10</displayname>
          <sortname>My Amazing Adventure</sortname>
        </series>
      </mainsection>
    </comic>

<comic>
      <id>12</id>
      <mainsection>
        <series>
          <displayname>My Amazing Adventure 12</displayname>
          <sortname>My Amazing Adventure</sortname>
        </series>
      </mainsection>
    </comic>

<comic>
      <id>2</id>
      <mainsection>
        <series>
          <displayname>My Amazing Adventure 2</displayname>
          <sortname>My Amazing Adventure</sortname>
        </series>
      </mainsection>
    </comic>


<comic>
      <id>3</id>
      <mainsection>
        <series>
          <displayname>My Amazing Adventure 3</displayname>
          <sortname>My Amazing Adventure</sortname>
        </series>
      </mainsection>
    </comic>

</comics>" ;

__xsort Function Used