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<?php $list = [ [ 'name' => 'blah', 'path' => 'A' ], [ 'name' => 'blah', 'path' => 'AA' ], [ 'name' => 'blah', 'path' => 'AB' ], [ 'name' => 'blah', 'path' => 'B' ], [ 'name' => 'blah', 'path' => 'BA' ], [ 'name' => 'blah', 'path' => 'BAA' ], ]; $result = array_reduce($list, function ($a, $c) { $l = substr($c['path'], 0, 1); isset($a[$l]) ? $a[$l]['children'][] = $c : $a[$l] = [ 'name' => $c['name'], 'path' => $c['path'], 'children' => [] ]; return $a; }, []); // to remove the letter keys, uncomment the next line // $result = array_values($result); var_export($result);
Output for 7.4.32, 8.1.23 - 8.1.33, 8.2.10 - 8.2.29, 8.3.0 - 8.3.28, 8.4.1 - 8.4.14, 8.5.0
array ( 'A' => array ( 'name' => 'blah', 'path' => 'A', 'children' => array ( 0 => array ( 'name' => 'blah', 'path' => 'AA', ), 1 => array ( 'name' => 'blah', 'path' => 'AB', ), ), ), 'B' => array ( 'name' => 'blah', 'path' => 'B', 'children' => array ( 0 => array ( 'name' => 'blah', 'path' => 'BA', ), 1 => array ( 'name' => 'blah', 'path' => 'BAA', ), ), ), )
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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