how to expand an array outward

[sfullman]

so I have this array (and it is one-indexed, not zero-indexed):

$array=array(
   1=>array(
      ..etc..
   ),
   2=>array(
      ..etc..
   ),
   3=>array(
      ..etc..
   ),
   4=>array(
      ..etc..
   ),
);

now I have this other array

$insert=array(
  ..etc..
);

and want to do this after an arbitrary index, let's say 2:

$array=array(
   1=>array(
      ..etc..
   ),
   2=>array(
      ..etc..
   ),

   3=>array(
     ..(this is the $insert array here)..
   ),

   4=>array(
      ..etc..
   ),
   5=>array(
      ..etc..
   ),
);

note that the array gets re-indexed after the insertion point.

I think I can write code to do it but wondered if php array functions might do this in just a few steps - havent' seen one yet that answers the need.

Thanks for this,
Samuel

[johanafm]

array_slice and array_merge.

$array=array(
	1=>array(
		'arr1'
	),
	2=>array(
		'arr2'
	),
	3=>array(
		'arr3'
	),
	4=>array(
		'arr4'
	),
);

$insert_array = array(8 => array('new stuff'));
$merged = array_merge(array_slice($array, 0, 2), $insert_array, array_slice($array, 2));

echo '<pre>'.print_r($merged,1).'</pre>';

But especially do note this, according to doc entry for array_merge

If all of the arrays contain only numeric keys, the resulting array is given incrementing keys starting from zero.

[sfullman]

that actually could work it's just that the array I have to work with comes out 1-based. Believe me I wish I could use something that simple. often php does "simplifications" like resetting the keys which on a low-level I'm sure make sense, but require I write "higher" level coding I'd rather not. Here's what I came up with - and the keys are preserved, but bumped up 1 after the insert:

function array_insert($array, $keyafter, $insert, $options=array()){
	/* Created 2010-09-13 by Samuel */
	//handle options
	extract($options);
	if(!$increment)$increment=1;
	if(!isset($appendToEnd))$appendToEnd=true;

//handle trivial conditions
if(!is_array($array))return $array;
if(!count($array)){
	return array(1=>$insert);
}
//insert the node
foreach($array as $n=>$v){
	$a[$n + ($doIncrement ? $increment : 0)]=$v;
	if($n==$keyafter){
		$doIncrement=$increment;
		$a[$n+$increment]=$insert;
	}
}
//append to end if $keyafter not reached
if(!$doIncrement && $appendToEnd)$a[$n + $increment]=$v;
return $a;
}
$array=array(
	1=>array(2,4,6,8),
	2=>array(3,6,9,12),
	3=>array(2,3,5,7,11,13,17),
	4=>array(log(10), pi(), 8.48191)
);
$insert=array(0,5,10,15,20);

echo '<pre>';

$array=array_insert($array,2,$insert);
print_r($array);

[johanafm]

I would probably rewrite my code to handle 0-based arrays, but if you insist on using integer indexing, prepend an extra element, then array_slice the rest of the array

$merged = array_merge(array(0), array_slice($array, 0, 2), $insert_array, array_slice($array, 2));
$merged = array_slice($merged, 1, null, true);