Sorting PHP arrays, keeping duplicates

Question

I have an associative array with the key of date, and a value of teams. For instance:

March 21, 2016 10:05 => 'Detroit vs. Philly'
March 21, 2016 7:05 =>'Toronto vs. Ottawa'
March 21, 2016 7:05 => 'Anahiem vs. Boston'
March 21, 2016 10:25 => 'Chicago vs. Winnipeg'

The problem is the RSS feed that I am parsing does not give me this data in an ordered fashion. So I need to order these games by the date, and when I add these fields in an associative array, duplicate dates (you can see that two games start at 7:05 on March 21st) are omitted because two keys can not be the same. I have tried to reverse the data, so that the key is the value and the value is the key and I can sort it this way, but when flip the array back, (array_flip($input);) the same problem occurs because again two keys cannot be the same.

I'm sure there is a simple way to handle this, but I'm going around in circles.

Any help would be very much appreciated.

<?php
      foreach ($feed->get_items() as $item): // this is my feed parser 
            $string = $item->get_title();    // gets each element
            preg_match_all('/\((.*?)\)/', $string, $out); 
            $timedate = ($out[1][2]);
            $array[$timedate] = $string; // creates an array with date as key, string data as values
          endforeach;  
?>

the date and time are the keys?, do note that keys are supposed to be unique, March 21, 2016 7:05 occurs twice — Kevin
– Kevin, Commented Mar 22, 2016 at 2:08
Without the code is hard to help you. Basically, you have to add an incrementing suffix to keys or to use a enumerated multidimensional array. — fusion3k
– fusion3k, Commented Mar 22, 2016 at 2:08

gabe. · Accepted Answer · 2016-03-22 02:59:46Z

To do what you want, you will have to put the data you have into a slightly more complex array, and then use the usort() function to sort it based on the key you would like to sort it on. Here is an example:

<?php                                                                                                                                                                                                                                       

// Multidimensional array of 'games'                                                                                                                                                                
$games[] = array('date' => 'March 21, 2016 10:05',                              
               'title' => 'Detroit vs Philly');                                 

$games[] = array('date' => 'March 21, 2016 7:05',                               
               'title' => 'Toronto vs Ottawa');                                 
$games[] = array('date' => 'March 21, 2016 7:05',                               
               'title' => 'Anaheim vs Boston');                                 
$games[] = array('date' => 'March 21, 2016 10:25',                              
               'title' => 'Chicago vs Winnipeg');                               

// Define a custom sort function to sort based on
//  the date index.  This will not sort properly
//  since I'm only using strcmp, but it works as 
//  an illustration.  For more details see: 
//  http://php.net/manual/en/function.usort.php
function cmp($a, $b)                                                            
{                                                                               
    return strcmp($a['date'], $b['date']);                                      
}                                                                            

// Sort the array
usort($games, "cmp");                                                           

print_r($games);

This will produce the following sorted array:

Array
(
[0] => Array
    (
        [date] => March 21, 2016 10:05
        [title] => Detroit vs Philly
    )

[1] => Array
    (
        [date] => March 21, 2016 10:25
        [title] => Chicago vs Winnipeg
    )

[2] => Array
    (
        [date] => March 21, 2016 7:05
        [title] => Toronto vs Ottawa
    )

[3] => Array
    (
        [date] => March 21, 2016 7:05
        [title] => Anaheim vs Boston
    )

)

You will notice that the dates aren't exactly properly sorted since strcmp() is just doing a basic string comparison. You could add more functionality to the cmp() function we defined to convert the strings to php dates, and then do actual date comparisons on them instead.

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