php importance of a number in a set of numbers - php

Question

I have a set of numbers e.g.
$input = array(1, 4, 7, 4, 9, 4, 8, 6, 2, 8, 7, 7, 4, 5, 3);
I am trying to work out the importance of each number based on the following rule:
As the sequence gets longer the numbers get less significant, and each time a number is mentioned then it will improve the relevance (how much depends on its position in the
sequence).
I am expecting something like:
Array(
'4' => 90%
'1' => 75%
'7' => 60%
....
)
So 4 is the most inportant, followed by 1 and then 7 etc. Note that the output is completely fabricated but gives in indication that 4 should be the most important. I believe I want some kind of linear solution.

Answer 1

Is this more of what you were thinking? Answer based on stillstanding
$numbers = array(1, 4, 7, 4, 9, 4, 8, 6, 2, 8, 7, 7, 4, 5, 3);
$weight = array();
$count = count($numbers);
for ($i=0; $i<$count; $i++) {
if (!isset($weight[$numbers[$i]])) $weight[$numbers[$i]] = 1;
$weight[$numbers[$i]] += $count + pow($count - $i, 2);
}
$max = array_sum($weight);
foreach ($weight as &$w) {
$w = ($w / $max) * 100;
}
arsort($weight);
result:
Array
(
[4] => 34.5997286296
[7] => 17.3677069199
[1] => 16.3500678426
[8] => 10.0407055631
[9] => 9.29443690638
[6] => 5.42740841248
[2] => 4.40976933514
[5] => 1.35685210312
[3] => 1.15332428765
)

Answer 2

$numbers=array(1, 4, 7, 4, 9, 4, 8, 6, 2, 8, 7, 7, 4, 5, 3);
$weight=array();
$count=count($numbers);
for ($i=0; $i<$count; $i++) {
if (!isset($weight[$numbers[$i]]))
$weight[$numbers[$i]]=1;
$weight[$numbers[$i]]*=$count-$i;
}
var_dump($weight);
Result:
Array
(
[1] => 15
[4] => 5040
[7] => 260
[9] => 11
[8] => 54
[6] => 8
[2] => 7
[5] => 2
[3] => 1
)

Answer 3

This algorithm is fairly simplistic, but I think it accomplishes what you're looking for.
Given that you have the sequence you described above and it is stored in an array called $sequence
$a = array();
for($i=0;$i<count($sequence);$i++)
{
//calculate the relevance = 1/position in array
$relevance = 1/($i+1);
//add $relevance to the value of $a[$sequence[$i]]
if(array_key_exists((string)$sequence[$i],$a))
$a[(string)$sequence[$i]] += $relevance;
else
$a[(string)$sequence[$i]] = $relevance;
}
return $a;