Sort XML data by newest to oldest in PHP - php

Question

I've got this code that works well now but thought it would be useful to have the Observed Data start from the newest date to the oldest. How can I flip only the Observed Data? Here is the code (Sorry if it doesn't look right on here, still getting use to posting on this site):
<?php
$url = "http://r7j8v4x4.map2.ssl.hwcdn.net/NOD_R.xml";
$xml = simplexml_load_file($url);
?>
<?php foreach ($xml->RESULTSET[0]->ROW as $MSG) :?>
<?php echo '<h4>', $MSG->MSG_TXT; '</h4>'; ?>
<?php endforeach; ?>
<!-- Table Style -->
<style>
table {border: 2px solid #fff;}
table td {height: 15px;}
table td {border: 1px solid #fff; }
table tr {border: 1px solid #fff; }
table td {padding: 3px; }
</style>
<h2>Observed Data</h2>
<table>
<div style="overflow-x:auto;">
<thead>
<tr>
<td><span style="margin:0px; font-weight:bold">Day</span></td>
<td><span style="margin:0px; font-weight:bold">Time(EST)</span></td>
<td><span style="margin:0px; font-weight:bold">Reservoir Elev.(behind dam)*</span</td>
<td><span style="margin:0px; font-weight:bold">Tailwater Elev.(below dam)*</span></td>
<td><span style="margin:0px; font-weight:bold">Avg Hourly Discharge* </span></td>
</tr>
</thead>
<tbody>
<?php foreach ($xml->RESULTSET[1]->ROW as $obs) :?>
<tr>
<td><?php echo $obs->OBS_DAY; ?></td>
<td><?php echo $obs->OBS_HR; ?></td>
<td><?php echo $obs->UPSTREAM_ELEV; ?></td>
<td><?php echo $obs->DOWNSTREAM_ELEV; ?></td>
<td><?php echo $obs->AVG_HOURLY_DISCHARGE; ?></td>
</tr>
<?php endforeach; ?>
</tbody>
</table>
<h2>Predicted Data</h2>
<table>
<div style="overflow-x:auto;">
<thead>
<tr>
<td><span style="margin:25px; font-weight:bold">Day</span></td>
<td><span style="margin:5px; font-weight:bold">Average Inflow* </span</td>
<td><span style="margin:5px; font-weight:bold">Midnight Elevation*</span></td>
<td><span style="margin:5px; font-weight:bold">Average Outflow*</span></td>
</tr>
</thead>
<tbody>
<?php foreach ($xml->RESULTSET[2]->ROW as $pred) :?>
<tr>
<td><?php echo $pred->PREDICTED_DAY; ?></td>
<td><?php echo $pred->DAILY_AVG_INFLOW; ?></td>
<td><?php echo $pred->MIDNIGHT_ELEV; ?></td>
<td><?php echo $pred->DAILY_AVG_OUTFLOW; ?></td>
</tr>
<?php endforeach; ?>
</tbody>
</table>`

Answer 1

You can read them into arrays before you output.
foreach ($xml->RESULTSET[1]->ROW as $obs) {
$resultSet1[] = $obs;
}
foreach ($xml->RESULTSET[2]->ROW as $obs) {
$resultSet2[] = $obs;
}
That will make it easier for you to reverse them. Once they're in arrays there are various ways to do it. You can use array_reverse, a for loop with a decrementing index, or something like this:
<?php while ($obs = array_pop($resultSet1)) :?>
<tr>
<td><?php echo $obs->OBS_DAY; ?></td>
<td><?php echo $obs->OBS_HR; ?></td>
<td><?php echo $obs->UPSTREAM_ELEV; ?></td>
<td><?php echo $obs->DOWNSTREAM_ELEV; ?></td>
<td><?php echo $obs->AVG_HOURLY_DISCHARGE; ?></td>
</tr>
<?php endwhile; ?>