Finding the minimum value's key in an associative array

Question

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.

SilentGhost · Accepted Answer · 2009-10-19 12:22:12Z

121

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).

answered Oct 19, 2009 at 12:22

SilentGhost

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4 Comments

Blixt Over a year ago

That's a clever one =) Maybe you should mention that it returns a list of 1 or more values (unless the array is empty.)

Augie Gardner Over a year ago

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.

Enyby Over a year ago

@Augie Gardner current(array_keys($pets, min($pets)); - little bit faster

Eugen Mihailescu Over a year ago

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.

lexx · Accepted Answer · 2014-02-26 02:05:08Z

14

Thats how i did it.

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

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

I hope that helps

edited Feb 26, 2014 at 2:05

answered May 29, 2012 at 1:01

lexx

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Comments

Phill Pafford · Accepted Answer · 2009-10-19 12:25:42Z

3

Might try looking into these:

answered Oct 19, 2009 at 12:25

Phill Pafford

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1 Comment

Chris Harrison Over a year ago

The links above are to the horrible w3schools, here are the proper PHP manual links (to save you a few seconds): php.net/manual/en/function.natcasesort.php php.net/manual/en/function.natsort.php

Jeff Ober · Accepted Answer · 2009-10-19 12:27:37Z

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.

edited Oct 19, 2009 at 12:27

answered Oct 19, 2009 at 12:20

Jeff Ober

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1 Comment

Damien MATHIEU Over a year ago

You forgot to close a bracket. And using array_keys and min, as suggested by SilentGhost will be easier and faster.

Will B. · Accepted Answer · 2019-12-06 00:42:41Z

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);

musefan · Accepted Answer · 2011-12-21 12:47:48Z

-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

edited Dec 21, 2011 at 12:47

musefan

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answered Dec 21, 2011 at 12:42

Rohit Suthar Mumbai

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1 Comment

marcovtwout Over a year ago

The question is about finding the key, not just the value.

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