压缩关联的php数组

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.

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);

First thing that comes to my mind is something like this:

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

function array_pair($source)
{
    $output = array();
    do {
        list($key, $value) = array_splice($source, 0, 2);
        $output[$key] = $value;
    } while (!empty($source));

    return $output;
}

var_dump(array_pair($array));

Outputs an array just like you need it:

array(2) {
  ["red"]=>
  string(4) "blue"
  ["green"]=>
  string(6) "purple"
}

Will even work if you have an odd number of elements in your source array:

$array = array('red', 'blue', 'green', 'purple', 'odd');
var_dump(array_pair($array));

Results in:

array(3) {
  ["red"]=>
  string(4) "blue"
  ["green"]=>
  string(6) "purple"
  ["odd"]=>
  NULL
}

You can easily write your own function to do this:

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

function glue($arr) {
  while(count($arr) > 0) {
    $dst[array_shift($arr)] = array_shift($arr);
  }
  return $dst;
}

foreach(glue($src) as $key => $value)
print $key ." => ".$value . "
";

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

for($i = 0; $i < count($arr); $i++) {
    if($i % 2 == 0) {
         $result[$arr[$i]] = $arr[$i + 1];
    }
}

output :

array (size=2)
  'red' => string 'blue' (length=4)
  'green' => string 'purple' (length=6)

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

$count = 0;
while($count < count($originalArray))
   $compressedArray[$originalArray[$count++]] = 
       $count < count($originalArray) ? $originalArray[$count++] : null;

print_r($compressedArray);

You can see it running on http://ideone.com/CTGXQZ