Assign every two elements of a flat array to be rows of a new 2d with predefined keys

Question

I have an array as follows:

$alldatesandtimes = [
    "2016-10-04 00:00:01",
    "2016-10-04 23:59:59",
    "2016-10-05 00:00:01",
    "2016-10-05 23:59:59",
    "2016-10-06 00:00:01",
    "2016-10-06 23:59:59"
]

I want to assign datein as the index of first element and dateout to 2nd element. Then datein as the index of 3rd element and dateout to 4th element and so on and so forth to all the remaining elements.

So first index shall be datein and 2nd index shall be dateout then keep on up to the last element.

I have following code:

$keys = array();
$result = array();
for ($j = 0; $j < ((sizeof($alldatesandtimes)) / 2); $j++)
{
    $keys[] = "datein";
    $keys[] = "dateout";
}

for ($i = 0; $i < sizeof($alldatesandtimes); $i++)
{
    $result[][$keys[$i]] = $alldatesandtimes[$i];
}

it returns the following array:

$result = Array (
    [0] => Array (
        [datein] => 2016-10-04 00:00:01
    )
    [1] => Array (
        [dateout] => 2016-10-04 23:59:59
    )
    [2] => Array (
        [datein] => 2016-10-05 00:00:01
    )
    [3] => Array (
        [dateout] => 2016-10-05 23:59:59
    )
    [4] => Array (
        [datein] => 2016-10-06 00:00:01
    )
    [5] => Array (
        [dateout] => 2016-10-06 23:59:59
    )
)

but I want

$result = [
    'datein' => '2016-10-04 00:00:01',
    'dateout' => '2016-10-04 23:59:59',
    'datein' => '2016-10-05 00:00:01',
    ...

So I assumed from $result[][$keys[$i]] that you wanted multidimensional, if not then see @RobertParham comment. — AbraCadaver
– AbraCadaver, Commented Oct 6, 2016 at 20:56

AbraCadaver · Accepted Answer · 2016-10-06 20:52:45Z

3

You can chunk it into pairs and then combine the value pairs with the key pair:

foreach(array_chunk($alldatesandtimes, 2) as $pair) {
    $result[] = array_combine(['datein', 'dateout'], $pair);
}

answered Oct 6, 2016 at 20:52

AbraCadaver

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Comments

Robert Parham · Accepted Answer · 2016-10-06 20:55:37Z

0

Not nearly as fancy as abra's answer but...

$newDates = array();
$dateHolder = array();
foreach($alldatesandtimes as $k=>$v){
    $key = $k%2===0 ? "dateIn" : "dateOut";
    $newDates[$key] = $v;
    if(count($newDates)===2){
        $dateHolder[] = $newDates;
        $newDates = array();
    }
}
$alldatesandtimes = $dateHolder;

https://3v4l.org/BCoYd

answered Oct 6, 2016 at 20:55

Robert Parham

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Comments

score 0 · Accepted Answer · 2016-10-06 20:59:39Z

0

You can loop the array with incrementing the $i variable by two ( $i+2). This way you all get every second element. after that assign a new array to another array as follows

$result[]=array("datein"=>$arr[$i], "dateout" => $arr[$i+1]);

edited Oct 6, 2016 at 20:59

answered Oct 6, 2016 at 20:54

user2047029

3 Comments

Robert Parham Over a year ago

if you do it like that assuming $i is only incremented by one each loop, the enddate will always be the startdate for the next array.

user2047029 Over a year ago

I explicitly mentioned that the loop must increment $i+2 instead of $i++

Robert Parham Over a year ago

i didn't see that, but it would have been easier and more readable if you had just added the loop to the answer..

mickmackusa · Accepted Answer · 2025-03-23 06:39:43Z

0

Additional approaches:

Use a functional-style script to chunk then make associative arrays from each chunk. Demo

var_export(
    array_map(
        fn($pair) => array_combine(['datein', 'dateout'], $pair),
        array_chunk($alldatesandtimes, 2)
    )
);

Make a single pass over the input and use bit-wise operations to determine which element should receive certain data.

$i >> 1 effectively divides by 2 and removes any decimals.
$i & 1 determines if the variable is odd.

Code: Demo
```
$keys = ['datein', 'dateout'];
$result = [];
foreach ($alldatesandtimes as $i => $dt) {
    $result[$i >> 1][$keys[$i & 1]] = $dt;
}
var_export($result);
```

edited Mar 23 at 6:39

answered Mar 23 at 6:16

mickmackusa♦

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