recursive function php - php

Question

I have an array which looks like this
$dataArray = array (
0 =>
array (
'UserId' => '804023',
'ProjectCode' => 'RA1234',
'Role' => 'PI',
),
1 =>
array (
'UserId' => '804023',
'ProjectCode' => 'RA1234',
'Role' => 'PM',
),
2 =>
array (
'UserId' => '804023',
'ProjectCode' => 'A90123',
'Role' => 'CI',
),
3 =>
array (
'UserId' => '804023',
'ProjectCode' => 'A20022',
'Role' => 'PM',
),
)
I need it to look like this
$expected = array (
804023 =>
array (
'RA1234' =>
array (
0 => 'PI',
1 => 'PM',
),
'A90123' =>
array (
0 => 'PI',
),
'A20022' =>
array (
0 => 'CI',
),
),
)
I think this could be achieved generically using recursion as this is a scenario I am likely to come across many times
I have got this far passing in an array of keys that form the nested array keys i.e.
$keys=array("UserId","projectCode","Role");
but am just not seeing where to go from here any pointers?
public function structureData(array $data, array $keys)
{
//$structuredData = array();
foreach ($data as $key => $value)
{
$keyForData = array_slice($keys,0,1);
$remainingKeys = $keys;
array_shift($remainingKeys);
if (!array_key_exists($value[$keyForData[0]], $structuredData))
{
$count=count($remainingKeys);
$structuredData[$value[$keyForData[0]]] =array();
// this returns as expected array(804023 =>array ()); but subsequent recursive calls with the remaining data fail
}
}
return $structuredData);
}

Answer 1

You don't need recursion, just a loop:
foreach ($dataArray as $da) {
$expected[$da['UserId']][$da['ProjectCode']][] = $da['Role'];
}
var_export($expected);
/* output:
array (
804023 =>
array (
'RA1234' =>
array (
0 => 'PI',
1 => 'PM',
),
'A90123' =>
array (
0 => 'CI',
),
'A20022' =>
array (
0 => 'PM',
),
),
)
*/

Answer 2

A crude but functioning solution.
function structureData($data, $keys){
$out = array();
foreach($data as $row){
$subout = &$out;
foreach(array_slice($keys, 0, -1) as $key){
$value = $row[$key];
$subout = &$subout[$value];
}
$subout[] = $row[$keys[count($keys) - 1]];
}
return $out;
}
print_r(structureData($dataArray, array('UserId', 'ProjectCode', 'Role')));

Answer 3

Recursion? Nah. Try this:
function add_role($dataArray, $userid, $project_code, $role)
{
$dataArray[$userid][$project_code][] = $role;
}

Answer 4

Functional solution:
$t = array_gather_key($dataArray, function ($e) { return $e['UserId']; } );
$t = array_map(
function ($e) {
return array_gather_key($e,
function ($e) { return $e['ProjectCode']; },
function ($e) { return $e['Role']; } );
},
$t
);
With this higher-order function:
function array_gather_key($array, $func, $transf = null) {
$res = array();
foreach ($array as $elem) {
$key = $func($elem);
if (!array_key_exists($key, $res))
$res[$key] = array();
if ($transf === null)
$res[$key][] = $elem;
else
$res[$key][] = $transf($elem);
}
return $res;
}
This gives:
array(1) {
[804023]=>
array(3) {
["RA1234"]=>
array(2) {
[0]=>
string(2) "PI"
[1]=>
string(2) "PM"
}
["A90123"]=>
array(1) {
[0]=>
string(2) "CI"
}
["A20022"]=>
array(1) {
[0]=>
string(2) "PM"
}
}
}