PHP Compare specific characters betwen two arrays

Question

In PHP, I have array like this:

Array
(
    [0] => 09:26-DOWN
    [1] => 09:26-UP
    [2] => 09:26-UP
    [3] => 09:26-UP
    [4] => 09:26-UP
    [5] => 09:26-UP
    [6] => 09:26-UP
    [7] => 09:26-UP
    [8] => 09:26-DOWN
    [9] => 09:26-UP
    [10] => 09:26-UP
    [11] => 09:26-UP
    [12] => 09:26-UP
    [13] => 09:26-UP
    [14] => 09:26-UP
    [15] => 09:26-UP
    [16] => 09:26-UP
    [17] => 09:26-UP
)

and I want to compare it with below array, only with the last characters (UP and DOWN):

Array
(
    [0] => 09:31-DOWN
    [1] => 09:31-UP
    [2] => 09:31-UP
    [3] => 09:31-UP
    [4] => 09:31-UP
    [5] => 09:31-UP
    [6] => 09:31-UP
    [7] => 09:31-UP
    [8] => 09:31-UP
    [9] => 09:31-UP
    [10] => 09:31-UP
    [11] => 09:31-UP
    [12] => 09:31-UP
    [13] => 09:31-UP
    [14] => 09:31-UP
    [15] => 09:31-UP
    [16] => 09:31-UP
    [17] => 09:31-UP
)

So the purpose is to check if it up or down between the specific time.

Answer 1

Not exactly sure what you're trying to do, but here's a simple option. Assuming that the format of each element will always be the same, ie HH:II-[UP or DOWN] , you could do this:

$result = array();
foreach ($arr1 as $k=>$v) {
    $result[] = $v[6] . $arr2[$k][6];
}

Given your two arrays, $arr1 and $arr2 , this will yield a third array like:

Array
(
    [0] => DD
    [1] => UU
    [2] => UU
    [3] => UU
    [4] => UU
    ....
)

Then you can use this array's values, UU , DD , UD , DU , to figure out what is in each position. For example key 3 will have UU , so you know it is UP, UP....

See demo

---

Update Here's the one-liner version using array_map() :

$result = array_map(function($a, $b){return $a[6] . $b[6];}, $arr1, $arr2);

See demo 2

Answer 2

Try to use strstr() + trim() to cut apart state / status.

$changed = []; // to store changed statuses

foreach($old as $i => $value){
    $from = trim(strstr($value, '-'), '-');   // getting status (UP / DOWN) from first array
    $to   = trim(strstr($new[$i], '-'), '-'); // getting status (UP / DOWN) from second array

    if($from != $to){ // if statuses are different
        $changed[$i] = [
            'from' => $from,
            'to'   => $to
        ]; // add to changed array
    }
}

Full example:

<?php
header('Content-Type: text/plain; charset=utf-8');

$old = [
    '09:26-DOWN',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-DOWN',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP',
    '09:26-UP'
];

$new = [
    '09:31-DOWN',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP',
    '09:31-UP'
];

$changed = [];

foreach($old as $i => $value){
    $from = trim(strstr($value, '-'), '-');
    $to   = trim(strstr($new[$i], '-'), '-');

    if($from != $to){
        $changed[$i] = [
            'from' => $from,
            'to'   => $to
        ];
    }
}

print_r($changed);
?>

Output:

Array
(
    [8] => Array
        (
            [from] => DOWN
            [to] => UP
        )

)

Answer 3

Give the two arrays

<?php 

$array1 = array('UP', 'DOWN', 'UP', 'DOWN');
$array2 = array('UP', 'DOWN', 'DOWN', 'UP');

foreach ($array2 as $key => $new_value)
{
    $old_value = $array1[$key];
    $new_array[$key] = ($old_value <= $new_value ? (($old_value < $new_value) ? 'UP' : 'NO CHANGE') : 'DOWN');
}

var_dump($new_array);

Will output something like this

array(4) {
  [0]=>
  string(9) "NO CHANGE"
  [1]=>
  string(9) "NO CHANGE"
  [2]=>
  string(4) "DOWN"
  [3]=>
  string(2) "UP"
}