Remove values from array depending on conditions - php

Question

This is more of an algorithm problem than a PHP problem, but I can't seem to figure it out!
I've got a multi dimensional array as following :
[
210875 => ["2", "1"],
129096 => ["2", "2"]
]
There are 2 ids but there could be more. I want to keep in my table only 1 id depending on these conditions.
Pseudo code:
if a[0] == 1 and a[1] >= 1: # the id gets deleted right away without looking at other conditions
if a[0] >= 2 and a[1] == 2: # it stays if nothing below fits else it gets deleted
if a[0] >= 3 and a[1] == 3: # it stays if nothing below fits else it gets deleted
if a[0] >= 8 and a[1] == 4: # it stays if nothing below fits else it gets deleted
# ... etc
If two fit the same conditions then one of them randomly gets deleted.
For example (pseudo code):
a[0] == 2 and a[1] == 1
a[0] == 2 and a[1] == 2
I've tried doing the following, but I can't figure out how to dynamically have if-conditions made dependent on my algorithm :
$sub_array = array();
foreach($array as $k=>$v) {
if($v[0] == 1 && $v[1] == 1) continue;
if($v[0] >= 2 && $v[1] == 2) $sub_array[$k] = $v;
if($v[0] >= 6 && $v[1] == 3) $sub_array[$k] = $v;
if($v[0] >= 8 && $v[1] == 4) $sub_array[$k] = $v;
// etc ...
}
Also, when I do that, how to know which one is the highest in my sub array?

Answer 1

It is not entirely clear to me what your conditions are, but to me it looks like you really are giving a rank to each of your rows, where in the end you want to keep the row with the highest rank.
Even if my interpretation of your rules might not be exactly what you intended, you can tune it by adapting the scores in the code below. I would also suggest to swap the conditions so that the == comparison comes first. That will be a bit more efficient:
$keepKey = null;
$bestScore = -1;
foreach($array as $k=>$v) {
$score = 0;
if ($v[1] == 1 && $v[0] == 1) $score = 1;
if ($v[1] == 2 && $v[0] >= 2) $score = 2;
if ($v[1] == 3 && $v[0] >= 6) $score = 3;
if ($v[1] == 4 && $v[0] >= 8) $score = 4;
// ... etc ...
if ($score > $bestScore) {
$keepKey = $k;
$bestScore = $score;
}
}
$sub_array = [$keepKey => $array[$keepKey]]; // Only keep the entry with highest score
If it is important to really pick a random one in case of ties, then shuffle the keys before starting the loop:
$keepKey = null;
$bestScore = -1;
$keys = array_keys($array); // <---
shuffle($keys); // <
foreach($keys as $k) { // <
$v = $array[$k]; // <---
$score = 0;
if ($v[1] == 1 && $v[0] == 1) $score = 1;
if ($v[1] == 2 && $v[0] >= 2) $score = 2;
if ($v[1] == 3 && $v[0] >= 6) $score = 3;
if ($v[1] == 4 && $v[0] >= 8) $score = 4;
echo $score . "\n";
if ($score > $bestScore) {
$keepKey = $k;
$bestScore = $score;
}
}
$sub_array = [$keepKey => $array[$keepKey]];