Two arrays in foreach loop search reverse and return null - PHP

devwmed
April 22, 2023
209 views
2 votes
4 Answers

I’m trying to compare two PHP arrays with different information.

First array:

Array
(
    [B1] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
            [3] => 4
            [4] => 5
            [5] => 6
            [6] => 7
            [7] => 8
        )

    [B2] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
            [3] => 4
        )

    [B3] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
            [3] => 4
            [4] => 5
            [5] => 6
            [6] => 7
            [7] => 8
        )

    [B4] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
            [3] => 4
            [4] => 5
            [5] => 6
            [6] => 7
            [7] => 8
            [8] => 9
        )

)

Second array:

Array
(
    [1] => B4
    [2] => B3
    [3] => B1
)

Now I want this result:

Array
(
    [B1] => Array
        (
            [0] => ok
            [1] => ok
            [2] => ok
            [3] => ok
            [4] => ok
            [5] => ok
            [6] => ok
            [7] => ok
        )

    [B2] => Array
        (
            [0] => null
            [1] => null
            [2] => null
            [3] => null
        )

    [B3] => Array
        (
            [0] => ok
            [1] => ok
            [2] => ok
            [3] => ok
            [4] => ok
            [5] => ok
            [6] => ok
            [7] => ok
        )

    [B4] => Array
        (
            [0] => ok
            [1] => ok
            [2] => ok
            [3] => ok
            [4] => ok
            [5] => ok
            [6] => ok
            [7] => ok
            [8] => ok
        )

)

I’ve tried various PHP functions, but they didn’t return expected result.

I’ve tried various PHP functions such as in_array and stristr to get the differences, but they returns different results and empty arrays.

Hope someone can help me, and thanks.

Answers

Solution:

<?php

//fill the first array
$a = [
    "B1" => [1, 2, 3, 4, 5, 6, 7, 8],
    "B2" => [1, 2, 3, 4],
    "B3" => [1, 2, 3, 4, 5, 6, 7, 8],
    "B4" => [1, 2, 3, 4, 5, 6, 7, 8, 9],
];

//fill the second array
$b = ["B1", "B3", "B4"];

//loop through first array
foreach ($a as $aKey => $val) {
    //count the length of arrays
    $arrLength = count($a[$aKey]);

    //find the key from second array
    $found = false;
    foreach ($b as $bKey) {
        if ($aKey == $bKey) {
            $found = true;
            break;
        }
    }

    //loop through inner arrays and
    //set the null value or 'ok' text for every element
    for ($i = 0; $i < $arrLength; $i++) {
        if ($found) {
            $a[$aKey][$i] = "ok";
        } else {
            $a[$aKey][$i] = null;
        }
    }
}

print_r($a);
?>

The result is:

Array
(
    [B1] => Array
        (
            [0] => ok
            [1] => ok
            [2] => ok
            [3] => ok
            [4] => ok
            [5] => ok
            [6] => ok
            [7] => ok
        )

    [B2] => Array
        (
            [0] => 
            [1] => 
            [2] => 
            [3] => 
        )

    [B3] => Array
        (
            [0] => ok
            [1] => ok
            [2] => ok
            [3] => ok
            [4] => ok
            [5] => ok
            [6] => ok
            [7] => ok
        )

    [B4] => Array
        (
            [0] => ok
            [1] => ok
            [2] => ok
            [3] => ok
            [4] => ok
            [5] => ok
            [6] => ok
            [7] => ok
            [8] => ok
        )

)

Definition:
This solution stores the result inside the first array, that means data from the first array will be lost. If you want to keep the data you can check this answer to copy data to another array:
https://stackoverflow.com/a/17729234/10109156

Or, you can create a new array to store the result:

<?php

//fill the first array
$a = [
    "B1" => [1, 2, 3, 4, 5, 6, 7, 8],
    "B2" => [1, 2, 3, 4],
    "B3" => [1, 2, 3, 4, 5, 6, 7, 8],
    "B4" => [1, 2, 3, 4, 5, 6, 7, 8, 9],
];

//fill the second array
$b = ["B1", "B3", "B4"];

$result = [];

//loop through first array
foreach ($a as $aKey => $val) {
    //count the length of arrays
    $arrLength = count($a[$aKey]);

    //find the key from second array
    $found = false;
    foreach ($b as $bKey) {
        if ($aKey == $bKey) {
            $found = true;
            break;
        }
    }
    
    //create an empty inner array
    $result[$aKey] = [];

    //loop through inner arrays and
    //set the null value or 'ok' text for every element
    for ($i = 0; $i < $arrLength; $i++) {
        if ($found) {
            $result[$aKey][$i] = "ok";
        } else {
            $result[$aKey][$i] = null;
        }
    }
}

print_r($result);
?>

And result is same.

<?php

$array = array(
    "B1" => array(1, 2, 3, 4, 5, 6, 7, 8),
    "B2" => array(1, 2, 3, 4),
    "B3" => array(1, 2, 3, 4, 5, 6, 7, 8),
    "B4" => array(1, 2, 3, 4, 5, 6, 7, 8, 9),
);

foreach ($array as $key => $subarray) {
    if (count($subarray) == 8) {
        $array[$key] = array_fill(0, 8, "ok");
    } else {
        $array[$key] = array_fill(0, count($subarray), null);
    }
}

print_r($array);

trying with this code


$data = [
    "B1" => [1, 2, 3, 4, 5, 6, 7, 8],
    "B2" => [1, 2, 3, 4],
    "B3" => [1, 2, 3, 4, 5, 6, 7, 8],
    "B4" => [1, 2, 3, 4, 5, 6, 7, 8, 9],
];

$keys = ["B1", "B3", "B4"];

// Will contain the output
$out = [];

foreach( $data as $key => $values ){

    // Construct the output entry,
    // fill with okays if $key is present 
    // in the $keys array, or with
    // nulls otherwise
    $out[ $key ] = array_fill(
        0,
        count($values),
        in_array($key, $keys) ? 'ok' : null
    );
};

print_r($out);

$arr1 = [
  'B1' => [ 1, 2, 3, 4, 5, 6, 7, 8 ],
  'B2' => [ 1, 2, 3, 4 ],
  'B3' => [ 1, 2, 3, 4, 5, 6, 7, 8 ],
  'B4' => [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
];

$arr2 = [ 'B1', 'B3', 'B4' ];

$result = array_map(
  static fn($list, $key) => array_fill(0, count($list), in_array($key, $arr2, true) ? 'ok' : null),
  $arr1,
  array_keys($arr1)
);

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Two arrays in foreach loop search reverse and return null – PHP

Answers