压缩关联的php数组

Question

Assume the following array in PHP:

array('red','blue','green','purple');      

I would like the simplest and fasted method to make that array come out like this:

array('red'=>'blue','green'=>'purple');      

If there is a php function that already exists that does this, that would be even better. I'm running a php 5.4 and 5.5 both so there hopefully shouldn't be a problem.

Answer 1

Not necessarily the fastest approach, but perhaps it'll introduce a few people to some features of PHP that they weren't aware of before:

$isEven = function ($value) {
    return !($value & 1);
};

$isOdd = function ($value) {
    return $value & 1;
};

function keyfilter($values, $function) {
    return array_intersect_key(
        $values,
        array_filter(
            array_keys($values),
            $function
        )
    );
}

$colourArray = array('red','blue','green','purple');

$mi = new MultipleIterator(
    MultipleIterator::MIT_NEED_ANY | 
    MultipleIterator::MIT_KEYS_ASSOC
);
$mi->attachIterator(
    new ArrayIterator(
        keyfilter(
            $colourArray, $isEven
        )
    ),
    'key'
);
$mi->attachIterator(
    new ArrayIterator(
        keyfilter(
            $colourArray, $isOdd
        )
    ),
    'value'
);

$newColourArray = array();
foreach($mi as $details) {
    $newColourArray[$details['key']] = $details['value'];
}

var_dump($newColourArray);