Create an array based on multiple arrays by key

Question

Please help me to combine four arrays in one.

I have to compare main array keys and if the key of the secondaries arrays coincides, add them to the new array. I tried to combine different php functions, but without the expected result and nothing relevant.

This is the main array.

[0] => Array
(
    [1] => "Category1"
    [2] => "Category2"
    [3] => "Category3"
    [4] => "Category4"
)

These are the secondaries arrays

[1] => Array
(
    [1] "user_test_[1]" key 1 map to --> [1] Category1
    [2] "user_test_[2]" key 2 map to --> [2] Category2
    [3] "user_test_[3]" key 3 map to --> [3] Category3
    [4] "user_test_[4]" key 4 map to --> [4] Category4
)

[2] => Array
(
    2: "user_prod_[2]"  key 2 map to --> [2] Category2
    4: "user_prod_[4]"  key 4 map to --> [4] Category4
)

[3] => Array 
(
    [3] "user_uat_[3]"  key 3 map to --> [3] Category3
    [4] "user_uat_[4]"  key 4 map to --> [4] Category4
)

New array results in php format:

$array_result = array(
        'Category1'=>array(
                    'user_test_[1]'
                ), 
        'Category2'=>array(
                    'user_test_[2]', 
                    'user_prod_[2]'
                ),
        'Category3'=>array(
                    'user_test_[3]', 
                    'user_uat_[3]'
                ),
        'Category4'=>array(
                    'user_test_[4]', 
                    'user_prod_[4]',
                    'user_uat_[4]'
                )   
        );

Main array in in php format:

$array_cat = array(1=>"Category1", 2=>"Category2", 3=>"Category3", 4=>"Category4");

These are the secondaries arrays in php fromat:

$array_usrtest = array(1=>"user_test_[1]", 2=>"user_test_[2]", 3=>"user_test_[3]", 4=>"user_test_[4]");
$array_usruat = array(3=>"user_uat_[3]", 4=>"user_uat_[4]");
$array_usrprod = array(2=>"user_prod_[2]", 4=>"user_prod_[4]");

Expected results

array{
    ["Category1"]=>array(1)
    {
        [0]=>"user_test_[1]"
    }
    ["Category2"]=>array(2)
    {
        [0]=>"user_test_[2]"
        [1]=>"user_prod_[2]"
    }
    ["Category3"]=>array(3)
    {
        [0]=>"user_test_[3]"
        [2]=>"user_uat_[3]"
    }
    ["Category4"]=>array(3)
    {
        [0]=>"user_test_[4]"
        [1]=>"user_prod_[4]"
        [2]=>"user_uat_[4]"
    }
}

The guy was kind enough to supply the 4 functions to generate the arrays, although there's lack of an attempt I think this is an ok question and perfect low hanging fruit for newbies — IsThisJavascript
– IsThisJavascript, Commented Oct 29, 2019 at 15:00
Is there an error is your Expected Results. What is the logic for items with [4] getting put into the Category3 array? Should there be a Category4 in the Results? — ptoinson
– ptoinson, Commented Oct 29, 2019 at 15:37

MorganFreeFarm · Accepted Answer · 2019-10-29 15:23:01Z

1

Here is simple solution, which it's not very good, because it is solution for your specific values, but it is good start point and if you want, you can improve it:

<?php

$array_cat = array(1=>"Category1", 2=>"Category2", 3=>"Category3", 4=>"Category4");
$array_usrtest = array(1=>"user_test_[1]", 2=>"user_test_[2]", 3=>"user_test_[3]", 4=>"user_test_[4]");
$array_usruat = array(3=>"user_uat_[3]", 4=>"user_uat_[4]");
$array_usrprod = array(2=>"user_prod_[2]", 4=>"user_prod_[4]");

$result = [];

foreach ($array_cat as $k => $v) {
    $result[$v] = []; // fill result array with categories
}

$values = array_merge($array_usrtest, $array_usruat, $array_usrprod); // merge arrays into one (all items)

foreach ($values as $k => $value) { // iterate over all values
    preg_match('!\d+!', $value, $match); // get index in [index]
    $result['Category' . $match[0]][] = $value; // append values to category
}

echo '<pre>';
var_dump($result);

Result:

array(4) {
  ["Category1"]=>
  array(1) {
    [0]=>
    string(13) "user_test_[1]"
  }
  ["Category2"]=>
  array(2) {
    [0]=>
    string(13) "user_test_[2]"
    [1]=>
    string(13) "user_prod_[2]"
  }
  ["Category3"]=>
  array(2) {
    [0]=>
    string(13) "user_test_[3]"
    [1]=>
    string(12) "user_uat_[3]"
  }
  ["Category4"]=>
  array(3) {
    [0]=>
    string(13) "user_test_[4]"
    [1]=>
    string(12) "user_uat_[4]"
    [2]=>
    string(13) "user_prod_[4]"
  }
}

edited Oct 29, 2019 at 15:23

answered Oct 29, 2019 at 15:13

MorganFreeFarm

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1 Comment

Alexandru Para Over a year ago

Thanks for a good point to start. This working as expected. Indeed if I change the Category name without an index for example to something like this random string "DRONX2KAR", code need to be improved.

blupointmedia · Accepted Answer · 2019-10-29 15:10:11Z

1

I would say merge all array and then build the category array

$arrs = array_merge($array_usrtest, $array_usruat, $array_usrprod);
$categories = array_fill_keys($array_cat, []);

array_walk($arrs, function($item) use (& $categories){
  preg_match('#(.*)\[(\d)\]#', $item, $matches);
  $key = $matches[2];

  $categories['Category' . $key][] = $item;
});

print_r($categories);

answered Oct 29, 2019 at 15:10

blupointmedia

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Comments

Alexandru Para · Accepted Answer · 2019-10-29 20:01:19Z

Based on yours answers:

<?php

$array_cat = array(1=>"Category1", 2=>"Category2", 3=>"Category3", 4=>"Category4");
$array_usrtest = array(1=>"user_test_[1]", 2=>"user_test_[2]", 3=>"user_test_[3]", 4=>"user_test_[4]");
$array_usruat = array(3=>"user_uat_[3]", 4=>"user_uat_[4]");
$array_usrprod = array(2=>"user_prod_[2]", 4=>"user_prod_[4]");

$values = array_merge($array_usrtest, $array_usruat, $array_usrprod);
$result = [];

foreach ($array_cat as $key => $cat) { 
    foreach ($values as $k => $value) { // iterate over all values
        preg_match('!\d+!', $value, $match); // get index in [index]
        if ($key == $match[0]) {
            $result[$cat][] = $value; //append values to category
        }
    }
}
echo '<pre>';
var_dump($result);

?>

Result:

array(4) {
  ["Category1"]=>
  array(1) {
    [0]=>
    string(13) "user_test_[1]"
  }
  ["Category2"]=>
  array(2) {
    [0]=>
    string(13) "user_test_[2]"
    [1]=>
    string(13) "user_prod_[2]"
  }
  ["Category3"]=>
  array(2) {
    [0]=>
    string(13) "user_test_[3]"
    [1]=>
    string(12) "user_uat_[3]"
  }
  ["Category4"]=>
  array(3) {
    [0]=>
    string(13) "user_test_[4]"
    [1]=>
    string(12) "user_uat_[4]"
    [2]=>
    string(13) "user_prod_[4]"
  }
}

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