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Question

I have json file that i import into associative array. It is about some sort of social network simulation. I made a list of people, and a links which leads to their profile. Profiles contain user name, age, gender and a list of their friends and friends of friends. Now i have to make a list of suggested friends on the profile, but i have no idea how to do it. Little help?

Suggested friends: people in the group who know 2 or more direct friends of the chosen user but are not directly connected to the chosen user.

<?php 

 $str = file_get_contents("data.json");
 $json = json_decode($str, true);

 $i = $_GET['id'];
?>

This is how i import data from json file. I used get method for id transfer.

 {
    "id": 2,
    "firstName": "Rob",
    "surname": "Fitz",
    "age": 23,
    "gender": "male",
    "friends": [
      1,
      3
    ]
  },
  {
    "id": 3,
    "firstName": "Ben",
    "surname": "O'Carolan",
    "age": null,
    "gender": "male",
    "friends": [
      2,
      4,
      5,
      7
    ]
  },
  {
    "id": 4,
    "firstName": "Victor",
    "surname": "",
    "age": 28,
    "gender": "male",
    "friends": [
      3
    ]
  }

This is a part of json.

<?php 

            for($m = 0; $m < sizeof($json[$i-1]['friends']); $m++) { 

        ?>
<tr>
  <th scope="row"><?php echo $json[$json[$i-1]['friends'][$m] - 1]["id"]; ?></th>
  <td><?php echo $json[$json[$i-1]['friends'][$m] - 1]["firstName"]; ?></td>
  <td><?php echo $json[$json[$i-1]['friends'][$m] - 1]["surname"]; ?></td>
  <td><a href="profile.php?id=<?php echo $json[$json[$i-1]['friends'][$m] - 1]["id"]; ?>">Profile</a></td>
  <?php for($j = 0; $j < sizeof($json[$json[$i-1]['friends'][$m] - 1]["friends"]); $j++) { ?>
      <td><?php echo $json[$json[$json[$i-1]['friends'][$m] - 1]["friends"][$j] - 1]["firstName"]." ".$json[$json[$json[$i-1]['friends'][$m] - 1]["friends"][$j] - 1]["surname"]; ?></td>
<?php   } ?>
</tr>

This is how i got friends and friends of friends

Answer 1

I took a shot at a solution. I have 2 classes, one representing a person and the other representing a group.

Person contains his list of friends and some functions to support the queries you want to ask.

/**
 * Represents the group of people
 */
class Group {
    // List of everyone
    public $personList = [];

    // Add a person to the group
    function addPerson(Person $person) {
        $this->personList[$person->id] = $person;
        return $person;
    }

    // Find suggested friends for everyone
    // Return [
    //      ['id' => 1, 'suggested' => [2,3]],
    //      ['id' => 2, 'suggested' => [2,3]]
    // ]
    function suggestedFriendsForEveryone() {
        $uggestions = [];
        foreach($this->personList as $person) {
            $suggestions[] = ['id' => $person->id, 'suggested' => $this->suggestedFriends($person)];
        }
        return $suggestions;
    }

    // return list of suggested friends for a person
    function suggestedFriends(Person $person) {
        // walk through the list and 
        $a = [];
        foreach($this->personList as $p) {
            if ( $person->isSuggestedFriend($p) ) {
                $a[] = $p->id;
            }
        }
        return $a;
    }

    // Output list 
    function showAll() {
        foreach($this->personList as $p) {
            echo $p->friendsString() . "
";
        }
    }
}

class Person {
    public $id;
    public $friends;

    function __construct($id, $friends=[]) {
        $this->id = $id;
        $this->friends = $friends;
    }
    /**
     * person knows 2 or more of my direct friends but is not my friend
     */
    public function isSuggestedFriend(Person $person) {
        if ( $person->id == $this->id ) return false; // I am not my own suggested friend        
        if ( $this->isFriend($person) ) return false;
        // Friends that person has that are not my friends
        $common = $this->commonFriends($person);
        if ( count($common) > 1 ) return true;
        return false;
    }

    // am I a friend of this person
    public function isFriend(Person $person) {
        if ( $person->id == $this->id ) return false; // I am not my own friend
        return in_array($person->id, $this->friends);
    }

    // returns list of common friends
    public function commonFriends(Person $person) {
        $diff = array_intersect($person->friends, $this->friends);
        return $diff;
    }
    // Return a string version of friend list
    public function friendsString() {
        return "Person: {$this->id} [" . implode(', ', $this->friends) . ']';
    }
    // Return a string version of isSuggestedFriend
    public function isSuggestedFriendString(Person $person) {
        if ( $this->isSuggestedFriend($person) ) return "Person {$person->id} is a suggested friend for Person {$this->id}";
        else "Person {$person->id} is not a suggested friend for Person {$this->id}";
    }
}

$g = new Group;
$g->addPerson(new Person(3, [2,4,5]));
$g->addPerson(new Person(4, [1,2,3]));
$g->addPerson(new Person(5, [3]));
$g->addPerson(new Person(6));
$g->addPerson(new Person(7));
$g->addPerson(new Person(1, [2,3,4]));
$g->addPerson(new Person(2, [1,4]));

$g->showAll();

//echo implode(', ', $g->suggestedFriends($p1)) . "
";
$sl = $g->suggestedFriendsForEveryone();
echo "Suggested Friends
";
foreach($sl as $row) {
    echo "Person {$row['id']} suggested [" . implode(', ', $row['suggested']) . "]
";
}