Here is what I want to do:
$newArray = array();
foreach($student as $s){
$newArray[$s->id][$s->grade] = $s;
}
I want to sort the students by their grades (more of a group than a sort) but I just want the grades to be sorted not the id. I could have don't this:
$newArray[$s->id] = $s->grade
asort($newArray)
but I need the remaining data in $s. Also, there is huge chunk of data associated with each student which I want to maintain.
How can I achieve such a sorting?
Edit:
Sine you're working in a framework, best declare your sort callback as a member function (inside the same class as where you'll be needing it, of course):
private function sortCB(array $a, array $b)
{//the array type hinting in arguments is optional
$i = array_keys($a);//but highly recommended
$j = array_keys($b);
if (end($i) === end($j))
{
return 0;
}
//replace '>' with '<' if you want to sort descending
return (end($i) > end($j) ? 1 : -1);//this is ascending
}
Then, in the method where the actual sorting is needed:
uasort($theArray,array($this,'sortCB'));
For more examples, see the docs. I've added a full class example at the end of this (bulky) answer
I've tried this on writecodeonline, which isn't all too good at this kind of stuff, but this did work:
$foo = array_fill_keys(array('foo','bar','q','Bond'),array());
$i = '256';
foreach($foo as $k=>$v)
{
$foo[$k][$i] = $k;
$i = (string)((int)$i%2 === 0 ? ((int)$i/2)+1 : (int)$i*3);
}
function sortCB($a,$b)
{
$i = array_keys($a);
$j = array_keys($b);
if (end($i) === end($j))
{
return 0;
}
return (end($i) > end($j) ? 1 : -1);
}
uasort($foo,'sortCB');
var_dump($foo);
But since you're using a framework, you might do well declaring that function as a member function private function sortCB(array $a,array $b), and use it like so:
uasort($foo,array($this, 'sortCB'));
There might be some more info on how best to use this callback function in a class context here
Full example + usage (tested and working):
class test
{
public $foo = null;
public function __construct()
{
$this->foo = array_fill_keys(array('foo','bar','q','Bond'),array());
$i = '256';
foreach($this->foo as $k=>$v)
{
$this->foo[$k][$i] = $k;
$i = (string)((int)$i%2 === 0 ? ((int)$i/2)+1 : (int)$i*3);
}
}
private function sortCB($a,$b)
{
$i = array_keys($a);
$j = array_keys($b);
if (end($i) === end($j))
{
return 0;
}
return (end($i) > end($j) ? 1 : -1);
}
public function sortFoo()
{
uasort($this->foo,array($this,'sortCB'));
print_r($this->foo);
return $this->foo;
}
}
$bar = new test();
$arr = $bar->sortFoo();
You can do something like:
foreach($student as $s){
$newArray[$s->id] = $s;
}
usort($newArray, function ($a, $b) { return $a->grade - $b->grade; });
For later versions that don't support anonymous functions you can define comparison function first:
function sortByGrade($a, $b)
{
return $a->grade - $b->grade;
}
usort($newArray, 'sortByGrade');
But if you get this data from db it would be easier to order it in your sql query. If you use ORM you can use its associated method.
function sortCB($a,$b){...} and use usort($newArray,'sortCB');
ORDER BY grade DESC?