PHP: assign priority to array values and then sort by that priority

Question

Is there a way to assign a "priority score" to an array in PHP? Then sort based on that priority. Given my input:

Array(
  [princeton] => Princeton
  [stanford] => Stanford
  [yale] => Yale
  [mit] => MIT
  [harvard] => Harvard 
)

I would like the output to always have Harvard and Yale at the top, the rest alphabetically sorted:

Array(
  [harvard] => Harvard
  [yale] => Yale
  [mit] => MIT
  [princeton] => Princeton
  [stanford] => Stanford    
)

I checked out asort() which does the alphabetical and uasort() which is custom-defined, but I'm stuck on how I can "assign a priority". Any help would be appreciated!

I would handset them, there's only a couple, but I'm stuck at how to do the assigning. — user1899415
– user1899415, Commented Jan 29, 2014 at 0:09
removing and adding to top after sorting alphabetly seems trivial — user557846
– user557846, Commented Jan 29, 2014 at 0:11
With uasort, you would define the sorting between 2 items. If neither is Harvard or Yale, do a strcmp, if one of them is, make it sort before the other, if both are, return 0 (unless you want harvard to sort before yale always, in which case, you could once again return a strcmp when both are harvard or yale). — Wrikken
– Wrikken, Commented Jan 29, 2014 at 0:11

anthonygore · Accepted Answer · 2014-01-29 00:32:00Z

2

uasort will sort your array by your own comparison function. I've made the function place either Harvard or Yale first (the ordering of those two will be uncertain since you haven't specified) and sort the rest alphabetically.

function cmp($a, $b) {
    if ($a == 'Yale' || $a == 'Harvard') {
        return -1;
    } else if ($b == 'Yale' || $b == 'Harvard') {
        return 1;
    } else return strcmp($a, $b);
}

uasort($array, 'cmp');

edited Jan 29, 2014 at 0:32

answered Jan 29, 2014 at 0:25

anthonygore

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Comments

mickmackusa · Accepted Answer · 2020-09-08 12:50:24Z

1

Perhaps you were overthinking this.

sort by key
replace your short priority array with the alphabetized array

Code: (Demo)

$ivyLeaguers = [
  'princeton' => 'Princeton',
  'cornell' => 'Cornell',
  'stanford' => 'Stanford',
  'yale' => 'Yale',
  'mit' => 'MIT',
  'harvard' => 'Harvard'
];

ksort($ivyLeaguers);
var_export(
    array_replace(['harvard' => null, 'yale' => null], $ivyLeaguers)
);

Output:

array (
  'harvard' => 'Harvard',
  'yale' => 'Yale',
  'cornell' => 'Cornell',
  'mit' => 'MIT',
  'princeton' => 'Princeton',
  'stanford' => 'Stanford',
)

The null values are overwritten but their position is respected. This technique pulls the priority schools to the top of the list based on the matching keys.

answered Sep 8, 2020 at 12:50

mickmackusa♦

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Comments

Eugen Rieck · Accepted Answer · 2014-01-29 00:12:42Z

0

Assuming you have something like

$priotities=array(
  [harvard] => 1
  [yale] => 2
  [mit] => 3
  [princeton] => 4
  [stanford] => 5
)

you could

$final=$priorites;
sort(final);
foreach ($final as $k=>$v) 
  $final[$k]=$universities[$k];

answered Jan 29, 2014 at 0:12

Eugen Rieck

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