php: Keep only max values in an array? - php

Question

Given a simple array like
$testarr = array("Donna"=>3, "Luke" => 4, "Pete" =>4, "Lola" => 1);
How can I keep only the max values?
I am aware I could do a
max($testarr);
and then loop through the array removing values that differ, but maybe sg like array_filter, or a more elegant one liner solution is available.

Answer 1

Here is your one-liner using array_filter:
<?php
$testarr = array("Donna"=>3, "Luke" => 4, "Pete" =>4, "Lola" => 1);
$max = max($testarr);
$only_max = array_filter($testarr, function($item) use($max){ return $item == $max; });
var_dump( $only_max );
Output:
array(2) {
["Luke"]=>
int(4)
["Pete"]=>
int(4)
}
Note that the closure function is referencing $max. As suggested by #devon, referencing the original array would make the code shorter & general, in exchange for calculation efficiency.
$only_max = array_filter($testarr,
function($item) use($testarr){
return $item == max($testarr);
});

Answer 2

This will get you where you need to go:
<?php
function less_than_max($element)
{
// returns whether the input element is less than max
return($element < 10);
}
$array1 = array("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5);
$array2 = array("a" => 6, "b"=>7, "c"=>8, "d"=>9, "e"=>10, "f"=>11, "g"=>12);
$max = 3;
echo "Max:\n";
print_r(array_filter($array1, "less_than_max"));
echo "Max:\n";
print_r(array_filter($array2, "less_than_max"));
?>