Merging data of common keys in a same array

Question

so I have an array like this :-

$headers = array();
$headers[] = array("country" => "Netherlands", "city" => "Amsterdam");
$headers[] = array("country" => "Netherlands", "city" => "Tillsburg");
$headers[] = array("country" => "Sweden", "city" => "Stockholm");

I need it like :-

array("country" => "Netherlands", "city" => "Amsterdam,Tillsburg");
array("country" => "Sweden", "city" => "Stockholm");

How do I merge the values?

Here's what I have tried till now, but it doesn't seems to be working.

function merge($headers) {
    $final = [];
    foreach($headers as $current) {
        if(!in_array($current['country'], $final)) {
            $final[] = $current['country'];
        }
  }

  foreach($headers as $current) {
      $final[$current['country']]['city'] = $current['city'];
  }
  return $final;
}

Any help would be appreciated.

Possible duplicate of PHP Match two arrays on key value (like mysql join) — Jan
– Jan, Commented Oct 12, 2018 at 8:58

mickmackusa · Accepted Answer · 2018-10-12 09:44:09Z

0

Use country values as temporary associative keys to determine if concatenation is necessary.

Code: (Demo)

$headers[] = array("country" => "Netherlands", "city" => "Amsterdam");
$headers[] = array("country" => "Netherlands", "city" => "Tillsburg");
$headers[] = array("country" => "Sweden", "city" => "Stockholm");

foreach ($headers as $row) {
    if (!isset($result[$row['country']])) {
        $result[$row['country']] = $row; // store the whole row
    } else {
        $result[$row['country']]['city'] .= ",{$row['city']}";  // concatenate
    }
}

var_export(array_values($result)); // reindex the output array

Output:

array (
  0 => 
  array (
    'country' => 'Netherlands',
    'city' => 'Amsterdam,Tillsburg',
  ),
  1 => 
  array (
    'country' => 'Sweden',
    'city' => 'Stockholm',
  ),
)

edited Oct 12, 2018 at 9:44

answered Oct 12, 2018 at 9:35

mickmackusa♦

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Comments

Volod · Accepted Answer · 2018-10-12 09:49:36Z

0

Maybe this is not the best solution, but I test it, it works.

function merge($headers) {
    $final = array();
    foreach ($headers as $current) {
        if( !isset( $final[ $current['country'] ] ) ) {
            $final[$current['country']] = [
                'country' => $current['country'],
                'city'    => $current['city']
            ];
            continue;
      }
      $final[ $current['country'] ]['city'] = $final[ $current['country'] ]['city'] . ', ' . $current['city'];
    }

    return $final;
}

Output

array(2) { ["Netherlands"]=> array(2) { ["country"]=> string(11) "Netherlands" ["city"]=> string(20) "Amsterdam, Tillsburg" } ["Sweden"]=> array(2) { ["country"]=> string(6) "Sweden" ["city"]=> string(9) "Stockholm" } }

You can clear keys of result array if you want adding

$final = array_values($final);

before return statement

Demo

edited Oct 12, 2018 at 9:49

answered Oct 12, 2018 at 9:04

Volod

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1 Comment

Volod Over a year ago

sandbox.onlinephpfunctions.com/code/…

Rubin Porwal · Accepted Answer · 2018-10-12 09:55:09Z

0

$headers = array();
$headers[] = array("country" => "Netherlands", "city" => "Amsterdam");
$headers[] = array("country" => "Netherlands", "city" => "Tillsburg");
$headers[] = array("country" => "Sweden", "city" => "Stockholm");
$result = array();

foreach($headers as $key => $value) {
    $result[$value['country']][] = $value['city'];
}
$finalArray = array();
foreach($result as $k => $v) {
    $finalArray[] = array('country' => $k, 'city' => join(',', $v));
}

answered Oct 12, 2018 at 9:55

Rubin Porwal

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1 Comment

mickmackusa Over a year ago

Two loops is not optimal design.

Niklesh Raut · Accepted Answer · 2018-10-12 09:49:33Z

-1

Create another array with country name as key

<?php
$headers = array();
$headers[] = array("country" => "Netherlands", "city" => "Amsterdam");
$headers[] = array("country" => "Netherlands", "city" => "Tillsburg");
$headers[] = array("country" => "Sweden", "city" => "Stockholm");
$countries = array_unique(array_column($headers,"country"));

$newHeaders = array();
foreach($headers as $header){
    $newHeaders[$header["country"]]["city"][] = $header["city"];
}
print_r($newHeaders);

foreach($newHeaders as $key=>$headers){
    echo $key." City : ".implode(",",$headers['city'])."\n";
}
?>

Live Demo Link

Output would be like

Netherlands City : Amsterdam,Tillsburg
Sweden City : Stockholm

edited Oct 12, 2018 at 9:49

answered Oct 12, 2018 at 9:13

Niklesh Raut

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