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<?php $array = [ [ 2 => 'kategorie_01', 'tags' => [ 1 => 'tag_01', 2 => 'tag_02', ], ], [ 3 => 'kategorie_02', 'tags' => [ 2 => 'tag_02', ], ], [ 1 => 'Default', 'tags' => [ 1 => 'tag_01', 2 => 'tag_02', ], ], [ 2 => 'kategorie_01', 'tags' => [ 2 => 'tag_02', 3 => 'tag_03', ], ], ]; $result = []; foreach ($array as $set) { foreach ($set as $k => $v) { if ($k !== 'tags') { $cat = $v; if (!isset($ref[$v])) { $ref[$v] = $set; $result[] = &$ref[$v]; } } else { $ref[$cat]['tags'] += $v; } } } var_export($result);
Output for 8.0.1 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.28, 8.4.1 - 8.4.14, 8.4.16, 8.5.0 - 8.5.1
array ( 0 => array ( 2 => 'kategorie_01', 'tags' => array ( 1 => 'tag_01', 2 => 'tag_02', 3 => 'tag_03', ), ), 1 => array ( 3 => 'kategorie_02', 'tags' => array ( 2 => 'tag_02', ), ), 2 => array ( 1 => 'Default', 'tags' => array ( 1 => 'tag_01', 2 => 'tag_02', ), ), )
Output for 8.4.15
/bin/php-8.4.15: /usr/lib/libm.so.6: version `GLIBC_2.38' not found (required by /bin/php-8.4.15) /bin/php-8.4.15: /usr/lib/libm.so.6: version `GLIBC_2.35' not found (required by /bin/php-8.4.15) /bin/php-8.4.15: /usr/lib/libc.so.6: version `GLIBC_2.34' not found (required by /bin/php-8.4.15) /bin/php-8.4.15: /usr/lib/libc.so.6: version `GLIBC_2.38' not found (required by /bin/php-8.4.15)
Process exited with code 1.

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