I know this question is old, but I'm providing the following answer in response to another question that pointed here after being marked as a duplicate. This is another alternative I don't see mentioned in the current answers.
I know there's a function called max but that doesn't work with a multidimensional array like this.
You can get around that with array_column
which makes getting the maximum value very easy:
$arr = [['message_id' => 1,
'points' => 3],
['message_id' => 2,
'points' => 2],
['message_id' => 3,
'points' => 2]];
// max value
$max = max[array_column[$arr, 'points']];
Getting the associative key is where it gets a little more tricky, considering that you might actually want multiple keys [if $max matches more than one value]. You can do this with an anonymous function inside array_map, and use array_filter to remove the null values:
// keys of max value
$keys = array_filter[array_map[function [$arr] use [$max] {
return $arr['points'] == $max ? $arr['message_id'] : null;
}, $arr]];
Output:
array[1] {
[0]=>
int[1]
}
If you do end up with multiples keys but are only interested in the first match found, then simply reference $keys[0].
[PHP 4, PHP 5, PHP 7, PHP 8]
max — Find highest value
Description
Alternative signature [not supported with named arguments]:
max[array $value_array]:
mixed
Note:
Values of different types will be compared using the standard comparison rules. For instance, a non-numeric string will be compared to an int as though it were
0, but multiple non-numeric string values will be compared alphanumerically. The actual value returned will be of the original type with no conversion applied.
Caution
Be careful when passing arguments of different types because max[] can produce unpredictable results.
Parameters
valueAny comparable value.
valuesAny comparable values.
value_arrayAn array containing the values.
Return Values
max[] returns the parameter value considered
"highest" according to standard comparisons. If multiple values of different types evaluate as equal [e.g. 0 and 'abc'] the first provided to the function will be returned.
If an empty array is passed, then false will be returned and an E_WARNING error will be emitted.
Examples
Example #1 Example uses of max[]
See Also
- min[] - Find lowest value
- count[] - Counts all elements in an array or in a Countable object
keith at bifugi dot com ¶
6 years ago
The simplest way to get around the fact that max[] won't give the key is array_search:
This could also be done with array_flip, though overwriting will mean that it gets the last max value rather than the first:
To get all the max value keys:
deoomen ¶
3 months ago
Watch out after PHP 8.0!
Sample code:
Before PHP 8.0 will return int[0] but since PHP 8.0 above code returns string["hello"]!!
volch5 at gmail dot com ¶
8 years ago
max[] [and min[]] on DateTime objects compares them like dates [with timezone info] and returns DateTime object.
It works at least 5.3.3-7+squeeze17
marcini ¶
13 years ago
Note that max[] can compare dates, so if you write something like this:
you will get: 2009-03-15.
costinu ¶
10 years ago
max[null, 0] = null
max[0, null] = 0
Alex Rath ¶
12 years ago
Notice that whenever there is a Number in front of the String, it will be used for Comparison.
But just if it is in front of the String
ries at vantwisk dot nl ¶
13 years ago
I had several occasions that using max is a lot slower then using a if/then/else construct. Be sure to check this in your routines!
Ries
ReVo_ ¶
8 years ago
Sometimes you could need to get the max from an array which looks like this:
all max functions i see around don't provide a way to get the max value of the values in [example] key "b"
output: 43
michaelangel0 at mail.com ¶
15 years ago
Matlab users and others may feel lonely without the double argument output from min and max functions.
To have the INDEX of the highest value in an array, as well as the value itself, use the following, or a derivative:
johnphayes at gmail dot com ¶
16 years ago
Regarding boolean parameters in min[] and max[]:
[a] If any of your parameters is boolean, max and min will cast the rest of them to boolean to do the comparison.
[b] true > false
[c] However, max and min will return the actual parameter value that wins the comparison [not the cast].
Here's some test cases to illustrate:
1. max[true,100]=true
2. max[true,0]=true
3. max[100,true]=100
4. max[false,100]=100
5. max[100,false]=100
6. min[true,100]=true
7. min[true,0]=0
8. min[100,true]=100
9. min[false,100]=false
10. min[100,false]=false
11. min[true,false]=false
12. max[true,false]=true
php at rijkvanwel dot nl ¶
11 years ago
To get the largest key in an array:
sun at drupal dot org ¶
11 years ago
Note that max[] throws a warning if the array is empty:
So make sure your data isn't empty.
info at osworx dot net ¶
3 years ago
Be aware if a array like this is used [e.g. values from a shopping cart]:
The result will be: 39,27 and not - as expected - 175,80
So, to find the max value, use integer only like:
and you will get the correct result: 17580
harmor ¶
14 years ago
A way to bound a integer between two values is:
which is the same as:
So if you wanted to bound an integer between 1 and 12 for example:
Input:
Output:
1
1
6
12
12
levim at php dot net ¶
10 years ago
- This function is not actually recursive, but fulfills the requirement that it works on sub-arrays. I do this because PHP is not very good at recursion. I also did it because I enjoy doing things this way.
- It returns something of type int, never a string representation of an int. The exception is when you provide an array that does not contain any integers. It will then return NULL.
- It ignores non-array, non-int values.
blackmac01 at gmail dot com ¶
2 years ago
In response to: keith at bifugi dot com
If you want to find the specific key[s] that match the maximum value in an array where the values may be duplicated, you can loop through and perform a simple check:
This produces consistent results and will scale well in terms of performance, whereas functions like array_search and array_flip can lead to degraded performance when dealing with large amounts of data.
toon dot baeyens at gmail dot com ¶
10 years ago
A little function for multi-dimensional arrays:
Michael Blinn ¶
3 years ago
Be careful using max[] with objects, as it returns a reference not a new object.
chris at candm dt org dt uk ¶
1 year ago
A function to return the key of the max value of an array. For multiple max values, it will return the key of first. Change > to >= to get the last.
function array_max_key[$arr] {
$maxkey='';
$maxval=false;
array_walk[$arr,
function [&$cval,&$ckey] use[&$maxkey,&$maxval] {
if [$maxval === false || $cval > $maxval] {
$maxval = $cval;
$maxkey = $ckey;
}
}
];
return $maxkey;
}