Multidimensional Array- Grouping by month

Question

I'm trying to wade my way through working more with multidimensional arrays to decrease the number of SQL queries I'm having to make. The problem is, they are new to me. Can someone give me some direction how to accomplish this?

Here's an example of the array:

Array
(
    [0] => Array
        (
            [0] => 2013-07-01
            [1] => Andy
            [2] => Hopkins Module
        )

    [1] => Array
        (
            [0] => 2013-07-01
            [1] => Frank
            [2] => Rotation
        )

    [2] => Array
        (
            [0] => 2013-07-01
            [1] => James
            [2] => Morning Report
        )

    [3] => Array
        (
            [0] => 2013-08-01
            [1] => James
            [2] => Noon Conference
        )

This array continues on with a lot more names and months. The data is ordered by name, meaning all of James item's are listed in a group. Each group of names may have one or more data points. What I would like to do is loop through each month and print out the second and third values. I know how to do a while statement to print out everything, but I'm not sure how to group all of the data by month.

This is the wrong way. First, you should try to optimize your SQL in that way you do NOT have to work too much over arrays than later. — djot, Sep 28 '13 at 23:36
Here are some good ideas: http://stackoverflow.com/questions/2189626/group-a-multidimensional-array-by-a-particular-value (I **could** write the code, but it is better / more rewarding if you do it yourself). — Styxxy, Sep 28 '13 at 23:36
@djot, the data doesn't have to necessarily come from a SQL database. — Styxxy, Sep 28 '13 at 23:36
@Styxxy: No, but the OP says: "to decrease the number of SQL queries I'm having to make." ... Where does the data come from, shown here? From a database most likely. So doing a simple e.g. `SELECT * ...` and then work with arrays instead of doing a more advanced SQL query is - again - not the right way. — djot, Sep 28 '13 at 23:37
@djot: It is sorted by date currently, which is how it is printed out. I'm not sure how else I can optimize it. The data is coming from one SQL statement. Do you have any suggestions? — user2558042, Sep 29 '13 at 00:43
Your SELECT query should group for date or month, you name it. (`GROUP BY ...`) — djot, Sep 29 '13 at 00:47

score 1 · Accepted Answer · answered Sep 28 '13 at 23:55

Give this a try (it assumes the array you showed is assigned to the variable $old_array):

foreach ($old_array as $key => $value) {
  $new_array[$value[0]][] = array($value[1], $value[2]);
}
// Uncomment the next line to print the new array
// print_r($new_array);

score 0 · Answer 2 · answered Sep 29 '13 at 00:33

I was able to do it with a modified version of jerdiggity's code... and the only way I could get it to work is terribly ugly. Are these many nested loops common?

foreach ($incomplete as $key => $value) {
        $new_array[$value[0]][$value[1]][] = $value[2];
    }


    foreach($months as $k=>$v) {
        $format = formatDate($v);
        echo $format; // date formatted as readable
        foreach($new_array[$format] as $k1=>$v1){
            echo $k1.'<br>'; //name of person
            foreach($v1 as $k2=>$v2) {
                echo $v2.'<br>'; //third value or original array
            }
        }
    }

Multidimensional Array- Grouping by month

2 Answers2

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