Array manipulation php

Question

I need help for my program. All I looking for is creating an array based on id_comment (id in mySQL table) then store it into another array

Example : mySQL table

id | id_comment | weight
1  |     1      | 0.311925
2  |     1      | 1
3  |     1      | 0.122169
4  |     2      | 1
5  |     3      | 1

Expected array ouput :

array(
    [0]=>(0.311925, 1, 0.122169)
    [1]=>(1)
    [2]=>(1)
)

I've try to figure it out, but still can't make it work Here's my code (the output is not as I expect):

$id = 5;

$arrayVector = array();

for ($i=1; $i <= $id; $i++) { 
    $a= mysqli_query($db, "SELECT weight FROM data_latih_model WHERE id_comment='$i'")or die("Error : ".mysqli_error($db));

    while ($b=mysqli_fetch_assoc($a)) {
        $arrayVector[] = array('key'=>$i,'value'=>$b['weight']);
    }
}

print_r($arrayVector);

Thank you for help.

Answer 1

You can use GROUP_CONCAT() in MySQL to fetch all the weights where the id is the same, and put that into a string separated by a given separator. Then, to reduce redundancy, instead of running the query inside a loop, run it once, with a BETWEEN clause.

$id = 5;
$vector = array();
$kelas = array();
$arrayVector = array();
$a = mysqli_query($db, "SELECT id_comment, GROUP_CONCAT(`weight`, SEPARATOR ', ') as weight_grouped, kelas FROM data_latih_model WHERE id_comment BETWEEN 1 AND $i")or die("Error : ".mysqli_error($db));

while ($b = mysqli_fetch_assoc($a)) {
    $arrayVector[] = array($b['id_comment'] => $b['weight_grouped']);
    $kelas[] = $b['kelas'];
}

Answer 2

change

$arrayVector[] = array('key'=>$i,'value'=>$b['weight']);

To

$arrayVector[$i][] = $b['weight'];

That should solve your problem.