Foreach：对相同数据进行分组

I am attempting to group generated data from a foreach statement by date. I am using Kirby CMS but am having troubling accomplishing the following.

Goal (sudo):

date: 03/10/15
Take Over

date: 03/09/15
Video
Flash
Super GIF 2
Super GIF
Image

My Attempt:

date: 03/10/15
Take Over
date: 03/09/15
Video
date: 03/09/15
Flash
date: 03/09/15
Super GIF 2
date: 03/09/15
Super GIF
date: 03/09/15
Image

Code:

  <ul>
    <?php foreach($page->children()->visible()->sortBy('modified', 'desc')  as $projects): ?>
      <li>
        date: <?php echo $projects->modified('m/d/y') ?> <br>
        <a href="<?php echo $projects->url() ?>"><?php echo $projects->title()->html() ?></a>
      </li>
    <?php endforeach  ?>  
  </ul>

Second unsuccessful attempt:

  <ul>
      <?php foreach($page->children()->visible()->sortBy('modified', 'desc')  as $projects): ?>
       <li>
          <?php foreach($page->children()->visible()->sortBy('modified', 'desc')  as $project): ?>

            <?php 
              if($projects->modified('m/d/y') == $project->modified('m/d/y')) {
                echo $project->modified('m/d/y') . '<br>' . $project->title();
              }

            ?>

          <?php endforeach  ?>  
       </li>


    <?php endforeach  ?>  
  </ul>

Output:

03/10/15
Take Over
03/09/15
Video 03/09/15
Flash 03/09/15
Super GIF 2 03/09/15
Super GIF 03/09/15
Image
03/09/15
Video 03/09/15
Flash 03/09/15
Super GIF 2 03/09/15
Super GIF 03/09/15
Image
03/09/15
Video 03/09/15
Flash 03/09/15
Super GIF 2 03/09/15
Super GIF 03/09/15
Image
03/09/15
Video 03/09/15
Flash 03/09/15
Super GIF 2 03/09/15
Super GIF 03/09/15
Image
03/09/15
Video 03/09/15
Flash 03/09/15
Super GIF 2 03/09/15
Super GIF 03/09/15
Image

Create a variable to hold the current date - $currentDate, then check if the $projects->modified('m/d/y') matches the $currentDate and if not, set it as the $currentDate and echo it-

  <?php $currentDate = ''; ?>
  <ul>
    <?php foreach($page->children()->visible()->sortBy('modified', 'desc')  as $projects): ?>
      <li>
        <?php if($projects->modified('m/d/y') != $currentDate) { $currentDate = $projects->modified('m/d/y'); ?>
        date: <?php echo $projects->modified('m/d/y') ?> <br>
        <?php } ?>
        <a href="<?php echo $projects->url() ?>"><?php echo $projects->title()->html() ?></a>
      </li>
    <?php endforeach  ?>  

edited - if you want the breaks between the dates, you can close/open the <li>/</li> inside the if

  <?php $currentDate = ''; ?>
  <ul>
    <?php foreach($page->children()->visible()->sortBy('modified', 'desc')  as $projects): ?>
      <li>

        <?php if($projects->modified('m/d/y') != $currentDate) { 
            if($currentDate != '') { echo "</li><li>"; } // if not the 1st date, add a blank space/li before the next date 
            $currentDate = $projects->modified('m/d/y'); ?>
        date: <?php echo $projects->modified('m/d/y') ?>
        <?php } ?>

        <br><a href="<?php echo $projects->url() ?>"><?php echo $projects->title()->html() ?></a>

    <?php endforeach  ?>  
      </li>
  </ul>

Essentially what you probably want to do is re-organize your list into containers.

** Note: all untested, but should be close **

This can be as simple as something like:

$containers = [];
foreach ($bar as $foo) {
  $containers[$foo['date']][] = $foo
}

ksort($containers);

If you're using PHP5.5+, you're in even more luck:

$containers = array_column($bar, null, 'date');
ksort($containers);

This should get you the structure you need for your looping:

$dates = array_keys($containers);
foreach ($dates as $container) {
  echo 'date: '.$container;
  var_dump($containers[$container]);
}