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I have been working on this problem for a couple days now. I would like to make an array that contains a list of user id's with the sum of value1 and value2 from the list of data below.

User ID value1 Value2
1        21      2
2        2       6
3        4       43
1        3       9
2        17      8
1        12      28

Here is an amalgamation of my various attempts. It is all wrong, but conveys what I am trying to do.

$members_list = array();
if(!in_array($user_id, $members_list)){
    array_push($members_list, $user_id);
}
foreach($data_table as $data_row){
    if($user_id == $data_row['$user_id']) {
        $members_list[$_user_id]['total'] = $members_list[$user_id]['total'] + $data_row['value1'] + $data_row['value2'];
    }
}

I am trying to teach myself how to program and probably lacking a fundamental understanding of how to organise and loop through multi-dimensional arrays. Hoping someone can help me clear this up. Thanks in advance.

share|improve this question
    
Can you please post the result of var_dump($data_table)? –  Dinistro Oct 21 '14 at 13:34

3 Answers 3

up vote 0 down vote accepted

I think I would write:

$members_list = array();
foreach($data_table as $data_row){
  if(isset($members_list[$data_row['$user_id']]) == false ) {
    $members_list[$user_id] = 0;
  }
  $members_list[$_user_id]['total'] += ($data_row['value1'] + $data_row['value2']);
}

Or are you planing on adding more information about each member? in that case you could have an array instead of a number for each member.

in that case you use

 $members_list[$user_id] = array();
 $members_list[$user_id]['total'] = 0;

in the if statement.

share|improve this answer
up vote 0 down vote

Well, this is going to be a dummy example of what I think you're looking for...

First, here is your multi-dimensional array:

$users = array(
    array('user_id' => 1, 'value1' => 21, 'value2' => 2),
    array('user_id' => 2, 'value1' => 2, 'value2' => 6),
    array('user_id' => 3, 'value1' => 4, 'value2' => 43),
    array('user_id' => 1, 'value1' => 3, 'value2' => 9),
    array('user_id' => 2, 'value1' => 17, 'value2' => 8),
    array('user_id' => 1, 'value1' => 12, 'value2' => 28)
);

Second, loop through the list of users, grouped by user_id and adding a third key (total value) for each user:

$members_list = array();
foreach ($users as $user)
{
    if ( !array_key_exists($user['user_id'], $members_list) )
        $members_list[$user['user_id']] = $user['value1'] + $user['value2'];
    else
        $members_list[$user['user_id']] += $user['value1'] + $user['value2'];
}
share|improve this answer
up vote 0 down vote

So your array should look like this:

$myArray = array("userId" => array("value1", "value2"));

So I'm gonna use a few values from your list as an example:

$users = array(
    1 => array(21, 2),
    2 => array(2, 6),
    3 => array(4,43)
);

So with this array feel free to test it out with this:

foreach ($users as $user => $values) {
    echo "<b>USER:".$user."</b> -> ";
    $sum = 0;
    foreach ($values as $value) {
        echo $value.", ";
        $sum = $sum + $value;
    }
    echo " Sum: ".$sum."<br>";
}

You should get this output:

USER:1 -> 21, 2, Sum: 23
USER:2 -> 2, 6, Sum: 8
USER:3 -> 4, 43, Sum: 47

Does that help you?

share|improve this answer
    
Yes. tyvm. I understand now that you can have a key/value pair where the value is also and array or key=>value. Much appreciated. –  user2949794 Oct 21 '14 at 14:18
    
no worries. please vote up for the trouble :) –  just some guy Oct 21 '14 at 14:35

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