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up vote 0 down vote favorite

I have a multidimensional array which I want to convert to individual arrays.

Original array is 

$hos_pabsl = array(
    0 =>
    array(
        'tile_id' => '1',
        'tile_type' => '4',
        'title' => 'Introduction',
        'topicNum' => '1',
        'topicTitle' => 'Introduction',
        'subNum' => NULL,
    ),
    1 =>
    array(
        'tile_id' => '2',
        'tile_type' => '9',
        'title' => 'Beer',
        'topicNum' => '2',
        'topicTitle' => 'Beer',
        'subNum' => NULL,
    ),
    2 =>
    array(
        'tile_id' => '3',
        'tile_type' => '4',
        'title' => 'Methods of Brewing',
        'topicNum' => '2',
        'topicTitle' => 'Beer',
        'subNum' => NULL,
    ),
    3 =>
    array(
        'tile_id' => '4',
        'tile_type' => '11',
        'title' => 'Beer Styles',
        'topicNum' => '2',
        'topicTitle' => 'Beer',
        'subNum' => '',
    ),
);

I want to convert this array into individual arrays named 'tile_id' , 'tile_type' , ....

Currently I am doing it the following way !

$tile_id = [];
$tile_type = [];
$title = [];
$topicNum = [];
$topicTitle= [];
$subNum = [];

foreach($hos_pabsl as $val){
    array_push($tile_id, $val['tile_id']);
    array_push($tile_type, $val['tile_type']);
    array_push($title, $val['title']);
    array_push($topicNum, $val['topicNum']);
    array_push($topicTitle, $val['topicTitle']);
    array_push($subNum, $val['subNum']);
}

Problem 1: IS this the most efficient way (in terms of speed) to do this operation?

Problem 2:
The $hos_pabsl array's index (or keys) are always going to be sequential. However, my problem is that for second array (at level 2 OR $hos_pabsl[0]) the index (or keys) might increase or decrease.
E.g. all arrays in might have only 2 items 'tile_id' & 'title'. OR might have one extra item 'description'. So how can I make the above operation dynamic ?

To Solve problem 2, I have thought of using array_keys to extract names first $names = array_keys($hos_pabsl[0]) then using those names as array names like ${$names[0]} =[]. Again I don't think this is the right/efficient way to do this.



Any guidance on this would be really appreciated.

share|improve this question
1  
Problem1: Micro-optimalization has little to no effect here. Go with the flow. –  OptimusCrime May 1 '14 at 23:32
    
What do you want the result to look like and why? –  AbraCadaver May 1 '14 at 23:33
    
I want to result to have individual arrays. E.g. $tile_id=Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4); and $title = Array ( [0] => Introduction [1] => Beer [2] => Methods of Brewing [3] => Beer Styles); and $topicTitle = [0] => Introduction [1] => Beer [2] => Beer [3] => Beer); and so on and so forth.. I am getting the original array from DB and I need individual array for separate unrelated processing in different functions. –  phpLearner May 1 '14 at 23:36

3 Answers 3

up vote 2 down vote accepted

If you're running PHP 5.5, then you can use array_column()

$tile_id = array_column($hos_pabsl, 'tile_id');
$tile_type = array_column($hos_pabsl, 'tile_type');
... etc

for versions of PHP earlier than 5.5, you can use array_map()

$tile_id = array_map(
    function ($value) { return $value['tile_id']; }, $hos_pabsl
);
$tile_type = array_map(
    function ($value) { return $value['tile_type']; }, $hos_pabsl
);
... etc
share|improve this answer
    
Don't know if this changed in PHP 5.5 but: Anonymous functions are created using create_function(String args, String body), not by simply embedding them. –  ccKep May 1 '14 at 23:47
    
Anonymous functions (closures) can be embedded as I've shown in my example since PHP version 5.3: you don't have to use create_function –  Mark Baker May 1 '14 at 23:53
    
Hi MarkBaker and @AbraCadaver I have php version 5.4.4. So I tried to mix both of your methods. foreach(array_keys(reset($hos_phsg)) as $key) { $$key = array_map( function ($value) { return $value[$key]; }, $hos_phsg ); } The error I am getting is that $key is undefined in $value[$key]. How can I pass this $key value for it to be dynamic ? –  phpLearner May 2 '14 at 0:12
    
foreach(array_keys(reset($hos_phsg)) as $key) { $$key = array_map( function ($value) use ($key) { return $value[$key]; }, $hos_phsg ); } –  Mark Baker May 2 '14 at 9:49
up vote 1 down vote

To go with Mark Baker's answer since I was already typing it:

foreach(array_keys(reset($hos_pabsl)) as $key) {
    $$key = array_column($hos_pabsl, $key);
}
share|improve this answer
    
Sorry I can accept only one answer. Your answer also helped. I am trying to use combination your answer and @MarkBaker 's answer. I tried to mix both of your methods. foreach(array_keys(reset($hos_phsg)) as $key) { $$key = array_map( function ($value) { return $value[$key]; }, $hos_phsg ); } The error I am getting is that $key is undefined in $value[$key]. How can I pass this $key value for it to be dynamic ? –  phpLearner May 2 '14 at 0:14
    
Thanks for reply. I had tried that assuming $key would be available in closure function because of variable scope. But it throws Missing argument 2 for {closure}() in error. –  phpLearner May 2 '14 at 0:22
1  
function ($value) use ($key) { return $value[$key]; }, –  Mark Baker May 2 '14 at 7:04
up vote -1 down vote

In terms of performance if the array is huge using a for instead of a foreach it will be faster.

$tile_id = array();
$tile_type = array();
$title = array();
$topicNum = array();
$topicTitle = array();
$subNum = array();

$hos_pabsl_sz = count($hos_pabsl);
for ($i = 0; $i < $hos_pabsl_sz; ++$i ) {
    $tile_id[$i] = $hos_pabsl[$i]['tile_id'];
    $tile_type[$i] = $hos_pabsl[$i]['tile_type'];
    $title[$i] = $hos_pabsl[$i]['title'];
    $topicNum[$i] = $hos_pabsl[$i]['topicNum'];
    $topicTitle[$i] = $hos_pabsl[$i]['topicTitle'];
    $subNum[$i] = $hos_pabsl[$i]['subNum'];
}
share|improve this answer
    
Isn't this exactly the same as what I am doing already? –  phpLearner May 1 '14 at 23:38
    
@user2834439 Yes, but you said you wanted something faster. foreach is slower than for phpbench.com. In most cases it doesn't matter but it still slower. –  Manolis Agkopian May 1 '14 at 23:40
    
Note that the phpbench.com benchmark is using foreach($array as $key => $val) rather than simply foreach($array as $val)... including the key can make a significant performance overhead when using foreach; but normally foreach will be faster to iterate an array than for –  Mark Baker May 1 '14 at 23:49
    
@MarkBaker I agree but it is allready about 3500% slower, I don't thing that including the key or not will have a huge difference. Anyway, the only way to be sure it to benchmark it by yourself. –  Manolis Agkopian May 1 '14 at 23:55
    
Check the Read Loop: foreach() vs. for() vs. while(list() = each()) figures, I think you've just found the first reference on the phpbench.com site (Modify Loop: foreach() vs. for() vs. while(list() = each())), not the appropriate one for this case –  Mark Baker May 1 '14 at 23:57

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