Echoing specific element IDs' values in multi-dimensional array - php

Question

I am programming a script to output sorted information grabbed from the PubMed Central API. My issue is that I would like to pull the first and second authors as well as the first an second keywords (for the purposes of this question, we can focus on just one). A good example of this is at $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'}->contrib->name->surname. I can, obviously, get the first name to print.
It is my understanding from reading other posts that I need a foreach loop to achieve what I desire. I do not, however, understand how to implement this in this context. My code is as follows:
<?php
$PMCID = 3545513;
$url = 'http://www.pubmedcentral.nih.gov/oai/oai.cgi?verb=GetRecord&identifier=oai:pubmedcentral.nih.gov:'.$PMCID.'&metadataPrefix=pmc_fm';
$xml = new SimpleXMLElement(file_get_contents($url));
?>
<table>
<tr>
<td>Journal Title</td><td>Year</td><td>Issue</td><td>NOC_Country</td><td>State</td><td>City</td><td>Primary Institution</td><td>Secondary Institution</td><td>First Author</td><td>Second Author</td><td>Topic</td><td>Target Behavior 1</td><td>Target Behavior 2</td><td>Population</td><td>Paper</td><td>Status</td>
</tr>
<tr>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'journal-meta'}->{'journal-title-group'}->{'journal-title'};?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'pub-date'}->year;?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->issue;?></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'}->contrib->name->surname;?>, <?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'}->contrib->name->{'given-names'};?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'}->contrib->name->surname;?>, <?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'}->contrib->name->{'given-names'};?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'title-group'}->{'article-title'};?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'kwd-group'}->kwd;?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'kwd-group'}->kwd;?></td>
<td></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'article-categories'}->{'subj-group'}->subject;?></td>
<td></td>
</tr>
</table>
Any help would be greatly appreciated!

Answer 1

Ended up with:
<table>
<tr>
<td><strong>Journal Title</strong></td><td><strong>Year</strong></td><td><strong>Issue</strong></td><td><strong>First Author</strong></td><td><strong>Second Author</strong></td><td><strong>Topic</strong></td><td><strong>Target Behavior 1</strong></td><td><strong>Target Behavior 2</strong></td><td><strong>Paper</strong></td>
</tr>
<?php
$PMCID = $_REQUEST['PMCID'];
$url = 'http://www.pubmedcentral.nih.gov/oai/oai.cgi?verb=GetRecord&identifier=oai:pubmedcentral.nih.gov:'.$PMCID.'&metadataPrefix=pmc_fm';
$xml = new SimpleXMLElement(file_get_contents($url));
?>
<tr>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'journal-meta'}->{'journal-title-group'}->{'journal-title'};?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'pub-date'}->year;?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->issue;?></td>
<?php
$n=0;
foreach($xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'} as $author){
echo "<td>" . $author->contrib->name->surname . ", ";
echo $author->contrib->name->{'given-names'} . "</td>";
$n++;
if($n==2) break;
}
unset($n);
unset($author);
?>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'title-group'}->{'article-title'};?></td>
<?php
$i=0;
foreach($xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'kwd-group'}->kwd as $keyword){
echo "<td>" . $keyword . "</td>";
$i++;
if($i==2) break;
}
unset($i);
unset($keyword);
?>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'article-categories'}->{'subj-group'}->subject;?></td>
</tr>
</table>