50

In PHP, say that you have an associative array like this:

$pets = array(
    "cats" => 1,
    "dogs" => 2,
    "fish" => 3
);

How would I find the key with the lowest value? Here, I'd be looking for cats.

Is there some built in PHP function that I've missed which does this? It would also be great if there was a solution that accounted for several values being identical, as below:

$pets = array(
    "cats" => 1,
    "dogs" => 1,
    "fish" => 2
);

Above, I wouldn't mind if it just output either; cats or dogs.

Thanks in advance.

Philip Morton
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6 Answers6

117

array_keys is your friend:

$pets = array(
    "cats" => 1,
    "dogs" => 2,
    "fish" => 3
);
array_keys($pets, min($pets));  # array('cats')

P.S.: there is a dup here somewhere on SO (it had max instead of min, but I can distinctly remember it).

SilentGhost
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    That's a clever one =) Maybe you should mention that it returns a list of 1 or more values (unless the array is empty.) – Blixt Oct 19 '09 at 12:25
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    min(array_keys($pets, min($pets)); will ensure that you get ONE single answer, not an array. That can be confusing to people who simply copy and paste this method. – Augie Gardner Jul 10 '13 at 16:39
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    @Augie Gardner current(array_keys($pets, min($pets)); - little bit faster – Enyby Jul 12 '13 at 20:02
  • The above code is elegant but not optimal. It involves several operations (finding miniumum of N elements, find N keys, find the key with the value in a subset N). A faster version would be a search algorithm. I never did a benchmark about this, though. – Eugen Mihailescu Apr 12 '15 at 10:52
14

Thats how i did it.

$pets = array(
    "cats" => 1,
    "dogs" => 2,
    "fish" => 3
);

array_search(min($pets), $pets);

I hope that helps

lexx
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3

Might try looking into these:

Phill Pafford
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    The links above are to the horrible w3schools, here are the proper PHP manual links (to save you a few seconds): http://php.net/manual/en/function.natcasesort.php http://php.net/manual/en/function.natsort.php – Chris Harrison Jul 23 '14 at 08:58
2
$min_val = null;
$min_key = null;
foreach($pets as $pet => $val) {
  if ($val < $min_val) {
    $min_val = $min;
    $min_key = $key;
  }
}

You can also flip the array and sort it by key:

$flipped = array_flip($pets);
ksort($flipped);

Then the first key is the minimum, and its value is the key in the original array.

Jeff Ober
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1

Another approach for retrieving a single string is by using a desirable sorting method and retrieving the first key directly by using key() on the sorted array. In this instance the key with the lowest value is desired, asort will sort from lowest to highest values and reset the internal pointer. To retrieve the reverse (highest to lowest) use arsort.

Example: https://3v4l.org/5ijPh

$pets = array(
   "dogs" => 2,
   "cats" => 1,
   "fish" => 3
);
asort($pets);
var_dump(key($pets));
//string(4) "cats"

$pets = array(
   "dogs" => 1,
   "cats" => 1,
   "fish" => 3
);
asort($pets);
var_dump(key($pets));
//string(4) "dogs"

Take note that all of the PHP array sorting methods will alter the array by-reference. To prevent altering the original array, create a copy of the array or use an Iterator.

$petsSorted = $pets;
asort($petsSorted);
key($petsSorted);
Will B.
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-3

find the highest value 

print max(120, 7, 8, 50);

returns --> 120

$array = array(100, 7, 8, 50, 155, 78);
print max($array);

returns --> 155

find the lowest value 

print min(120, 7, 8, 50);

returns --> 7

$array = array(50, 7, 8, 101, 5, 78);
print min($array);

returns --> 5

musefan
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Rohit Suthar Mumbai
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