PHP：将数组转换为索引数组

Question

Given I have an simple non-associative array $values of SomeObject items indexed by 0, 1, 2, etc.

What is the best syntax to construct associative array $valuesByIndex indexed by some value extracted from original items?

What I constructed is:

$key = function($val) {
   return $val->getSomeProperty();
};
$valuesByIndex = array_combine(array_map($key, $values), $values);

Which is pretty equals to:

$key = function($val) {
   return $val->getSomeProperty();
};

$valuesByIndex = [];
foreach ($values as $val) {
    $valuesByIndex[$key($val)] = $val;
}

Looking for pretty compact syntax.

Answer 1

In this piece:

$key = function($val) {
   return $val->getSomeProperty();
};

$valuesByIndex = [];
foreach ($values as $val) {
    $valuesByIndex[$key($val)] = $val;
}

We can simply replace $key($val) with the contents of the function $val->getSomeProperty() Which gives us

$valuesByIndex = [];
foreach ($values as $val) $valuesByIndex[$val->getSomeProperty()] = $val;

Because if the function returns this $val->getSomeProperty() we can just put it right in there and forgo that function completely.

However if this is from a DB call you may be able to use (in PDO) PDO::FETCH_GROUP which takes the first column of the Select and makes it the top level key.