How to apply default subarray values to an associative multidimensional array?

Question

I need help to combine multiple arrays. For example, I have 2 different arrays.

$array1 contains the id and amount. $array2 will have the date and the amount base on the id.

$array1 = [
  310 => 0,
  311 => 0,
  312 => 0,
  313 => 0,
  314 => 0,
  315 => 0
];

$array2 = [
  "2019-05-17" => [
    312 => 3000.00
  ],
  "2019-06-20" => [
    312 => 3000.00
  ],
  "2019-06-27" => [
    313 => 5000.00,
    315 => 3000.00
  ]
];

Final output that I want:

$merge = [
    "2019-05-17" => [
      310 => 0,
      311 => 0,
      312 => 3000.00,
      313 => 0,
      314 => 0,
      315 => 0
    ],
    "2019-06-20" => [         
      310 => 0,
      311 => 0,
      312 => 3000.00,
      313 => 0,
      314 => 0,
      315 => 0
    ],
    "2019-06-27" => [
      310 => 0,       
      311 => 0,
      312 => 0,
      313 => 5000.00,
      314 => 0,
      315 => 3000.0
    ],
];

May I know how to achieve it so that I will get like the $merge?

We expect to see a failed coding attempt in your question.

mickmackusa
– mickmackusa ♦

2019-11-03 09:54:12 +00:00
Commented Nov 3, 2019 at 9:54 — mickmackusa
– mickmackusa ♦, Commented Nov 3, 2019 at 9:54
Hi. We need to see what you tried. Thanks.

GBouffard
– GBouffard

2019-11-03 10:06:56 +00:00
Commented Nov 3, 2019 at 10:06 — GBouffard
– GBouffard, Commented Nov 3, 2019 at 10:06

mickmackusa · Accepted Answer · 2019-11-03 22:37:27Z

Do not iterate twice. Merge as you iterate in a single pass through the second array.

Merging the two arrays with the"union operator" (+) will result in unordered keyes (not that that is typically an issue with associative arrays). To use the default array as the "guide" for the subarrays' keys, call array_replace() as the merging function.

Code: (Demo)

foreach ($array2 as &$row) {
    $row += $array1;
    ksort($row);  // if you care
}

Or (Demo)

foreach ($array2 as &$row) {
    $row = array_replace($array1, $row);
}

Output:

array (
  '2019-05-17' => 
  array (
    310 => 0,
    311 => 0,
    312 => 3000.0,
    313 => 0,
    314 => 0,
    315 => 0,
  ),
  '2019-06-20' => 
  array (
    310 => 0,
    311 => 0,
    312 => 3000.0,
    313 => 0,
    314 => 0,
    315 => 0,
  ),
  '2019-06-27' => 
  array (
    310 => 0,
    311 => 0,
    312 => 0,
    313 => 5000.0,
    314 => 0,
    315 => 3000.0,
  ),
)

And if you're on php7.4 or higher, you can use array_map() with arrow syntax as a one-liner.

Code: (Demo)

var_export(array_map(fn($row) => array_replace($array1, $row),$array2));

Below php7.4 the array_map() syntax is considerably more verbose. Demo.

var_export(
    array_map(
        function($row) use ($array1) {
            return array_replace($array1, $row);
        },
        $array2
    )
);

Just for fun, here's an extra technique with nested looping (language constructs instead of function calls) and null coalescing (a kind of inline conditional expression).

Code: (Demo)

$merged = [];
foreach($array2 as $date => $row) {
    foreach ($array1 as $id => $value) {
        $merged[$date][$id] = $row[$id] ?? $value;
    }
}
var_export($merged);

Thank you for your guide. I am still learning in programming. I don't have the idea to do it. I will look more on array_map()

Eugene · Accepted Answer · 2019-11-03 09:42:00Z

1

You can use your first array like a template.

$newArray = [];
foreach($array2 as $date => $data) {
    $tmpArr = $array1;
    foreach ($data as $id=>$value) {
        if (!array_key_exists($id, $tmpArr)) {
            continue;
        }
        $tmpArr[$id] = $value;
    }
    $newArray[$date] = $tmpArr;
}

answered Nov 3, 2019 at 9:42

Eugene

1,7303 gold badges16 silver badges32 bronze badges

Comments

LetsSeo · Accepted Answer · 2019-11-03 09:46:49Z

1

4 line solution. Take a look at comments in the code.

$final = []; //Creates an empty array.
foreach ($array2 as $key => $value) {
    $final[$key] = $array1; #adds array1 to each key of array2 on new array.
}
$merge = array_replace_recursive($final, $array2); #merges new array with array2.

var_dump($merge); #returns the solution on your question.

answered Nov 3, 2019 at 9:46

LetsSeo

8757 silver badges21 bronze badges

Collectives™ on Stack Overflow

How to apply default subarray values to an associative multidimensional array?

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related