best data structer for such a cross html table build - php

Question

There are some groups which holds some data for example empty cars, reservated cars and cars which will return.. So if user want to see a cross table between car groups and dates,
I want to create a cross html table like this:
<table class="table table-striped table-bordered table-hover">
<tr>
<th colspan="2"></th>
<th>Date1</th>
<th>Date2</th>
<th>Date3</th>
</tr>
<!--Group1-->
<tr>
<td rowspan="4">Group1</td>
<td>Empty</td>
<td>5</td>
<td>12</td>
<td>3</td>
</tr>
<tr>
<td>On the Res</td>
<td>8</td>
<td>6</td>
<td>6</td>
</tr>
<tr>
<td>Will Return</td>
<td>8</td>
<td>6</td>
<td>6</td>
</tr>
<tr>
<td>Remains</td>
<td>-11</td>
<td>0</td>
<td>-9</td>
</tr>
<!--Group1 Ends -->
<!--Group1-->
<tr>
<td rowspan="4">Group2</td>
<td>Empty</td>
<td>5</td>
<td>12</td>
<td>3</td>
</tr>
<tr>
<td>On the Res</td>
<td>8</td>
<td>6</td>
<td>6</td>
</tr>
<tr>
<td>Will Return</td>
<td>8</td>
<td>6</td>
<td>6</td>
</tr>
<tr>
<td>Remains</td>
<td>-11</td>
<td>0</td>
<td>-9</td>
</tr>
<!--Group1 Ends -->
</table>
And here is the output of this html code:
What is the best php array structure for this kind cross table?
Thanks.

Answer 1

This is bound to get a variety of opinions. For what it's worth, this is one possible structure that would make sense and would be fairly straightforward to code against.
The "groups" could be the top-level keys, and the value for each group would be an array of arrays:
$table_data = [
'Group1' => [
[ 'Title' => 'Empty',
'Date1' => 5,
'Date2' => 12,
'Date3' => 3
],
[ 'Title' => 'On the Res',
'Date1' => 8,
'Date2' => 6,
'Date3' => 6
],
// etc...
],
'Group2' => [
[ 'Title' => 'Empty',
'Date1' => 5,
'Date2' => 12,
'Date3' => 3
],
[ 'Title' => 'On the Res',
'Date1' => 8,
'Date2' => 6,
'Date3' => 6
],
// etc...
],
// etc...
];
My thoughts on the PHP loop would be something like so:
foreach( $table_data AS $group => $rows ) {
$rowspan = count( $rows );
echo '<tr><td rowspan="' . $rowspan . '">' . $group . '</td>';
$tr = '';
foreach( $rows AS $row ) {
echo $tr . '<td>' . implode( '</td><td>', array_values( $row ) ) . '</td></tr>';
$tr = '<tr>';
}
}