PHP sorting a 2-dimensional array by multiple subkeys - php

Question

I have an array as follows:
//0-based index, 2 dimensions
$data = array(
array(
'name'=>'EJA210E',
'id'=>439,
'region_id'=>17,
.. other attributes ..
),
array(
'name'=>'EJA210E',
'id'=>440,
'region_id'=>3,
),
array(
'name'=>'EJA210E',
'id'=>439,
'region_id'=>15,
),
.. etc..
);
What would be sort, first by name, then by id, then by region_id? Sorting by any one of these is no problem; I would simply loop through and get the name attribute, then re-order, however doing this three times I do not understand how to do.

Answer 1

You can try array_multisort by passing different ordering columns as shown below :
$data = array(
array(
'name'=>'EJA210E',
'id'=>439,
'region_id'=>17,
),
array(
'name'=>'EJA210E',
'id'=>440,
'region_id'=>3,
),
array(
'name'=>'AJA210E',
'id'=>438,
'region_id'=>15,
)
);
// Obtain a list of columns
foreach ($data as $key => $row) {
$name[$key] = $row['name'];
$id[$key] = $row['id'];
$region[$key] = $row['region_id'];
}
// Sort the data with volume descending, edition ascending
// Add $data as the last parameter, to sort by the common key
array_multisort($name, SORT_DESC, $id, SORT_DESC,$region, SORT_DESC, $data);

Answer 2

You could use usort() with a custom sorting function. Here's an example:
function cmp($a, $b)
{
if ($a['name'] == $b['name']) {
if ($a['id'] == $b['id']) {
if ($a['region_id'] == $b['region_id']) {
return 0;
}
return $a['region_id'] < $b['region_id'] ? -1 : 1;
}
return $a['id'] < $b['id'] ? -1 : 1;
}
return ($a['name'] < $b['name']) ? -1 : 1;
}
usort($data, 'cmp');