Foreach通过数组，在数组中进行一些计算，然后创建新数组并合并回原始数组

Question

Having some difficulty trying to do this. I'm fetching an array of all submissions, and they are being returned in an array like this:

Array
(
    [0] => Array
        (
            [Submission] => Array
                (
                    [user_id] => 2
                    [title] => This is a test, only a test
                    [source] => http://www.testing.com
                    [slug] => this-is-a-test-only-a-test
                    [category] => misc
                    [created] => 2012-10-05 03:43:11
                    [id] => 110
                )

            [SubmissionsVote] => Array
                (
                    [0] => Array
                        (
                            [id] => 336
                            [user_id] => 2
                            [submission_id] => 110
                            [vote_type] => up
                        )

                )
                (
                    [1] => Array
                        (
                            [id] => 337
                            [user_id] => 4
                            [submission_id] => 110
                            [vote_type] => down
                        )

                )
        )
)

My intent is to loop through that returned array, and grab all the SubmissionsVote by vote_type == up and vote_type == down.

I then want to calculate a score (this example would return a score of 0 which is just: up - down. With that, I want to put that score into an array and append it to the end of the original one so it'd look like:

Array
(
    [0] => Array
        (
           [Submission] => Array
                (
                    [user_id] => 2
                    [title] => This is a test, only a test
                    [source] => http://www.testing.com
                    [slug] => this-is-a-test-only-a-test
                    [category] => misc
                    [created] => 2012-10-05 03:43:11
                    [id] => 110
                )

            [SubmissionsVote] => Array
                (
                    [0] => Array
                        (
                            [id] => 336
                            [user_id] => 2
                            [submission_id] => 110
                            [vote_type] => up
                        )

                )
                (
                    [1] => Array
                        (
                            [id] => 337
                            [user_id] => 4
                            [submission_id] => 110
                            [vote_type] => down
                        )

                )
        [SubmissionScore] => Array
        (
             [0] => 0
        )
        )
)

Here is what I am doing unsuccessfully:

    $votes = array();
    $totalScore = array();

    foreach ($submissions as $submission) {
        $vote = $submission['SubmissionsVote'];
        array_push($votes, $vote);
    }   

    for ($i = 0; $i < count($votes); $i++) {
        $downVotes = 0;
        $upVotes = 0;

        if ($votes[$i]['vote_type'] == 'down') {
            $downVotes += 1;
        } else if ($votes[$i]['vote_type'] == 'up') {
            $upVotes += 1;
        }   

        $score = $upVotes - $downVotes;
        $totalScore = array_push($totalScore, $score);
    }

Would love to get a little push in the right direction here.

Answer 1

I see at least two errors in your code :

• You never set SubmissionScore in your array to $totalScore value.
• Even if you add a $votes[$i]['SubmissionScore'] = $totalScore, that will not work, in PHP only object are passed by reference so $votes will only contain copy.

There are multiple possibility to resolve the problem but a reference in the foreach is a good choice :

foreach ($submissions as &$submission) {
    $totalScore = 0;
    foreach ($submission['SubmissionsVote'] as $vote) {
        if ($vote['vote_type'] == 'down') {
            $totalScore--;
        } else if ($vote['vote_type'] == 'up') {
            $totalScore++;
        }
    }
    $submission['SubmissionScore'] = $totalScore;
}

Each submission will now have a SubmissionScore based on up/down vote.