Remove item by its value from array inside a loop

Question

Given this working code:

$input_array = array(
    "192.168.1.100",
    "192.168.1.101",
    "192.168.1.100",
    "192.168.1.102",
    "192.168.1.103",
    "192.168.1.198",
    "192.168.1.101",
    "192.168.1.25",
    "192.168.1.109",
    "192.168.1.109",
    "192.168.1.109",
    "192.168.1.100",
    "192.168.1.58"
);

$final_array = array();

foreach ($input_array as $value) {
    //if the value is present more or eq 3 times
    if (count(array_keys($input_array, $value)) >= 3) {

        //Add it to final array
        $final_array[] = $value;

        //Echo in the console
        echo "IP $value  will be banned!" . PHP_EOL;

        //Clean up the input array
        foreach ($input_array as $k => $v) {
            if ($value == $v) {
                unset($input_array[$k]);
            }
        }
    }
}

How would you optimize the "Clean up the input array" phase? Is there a way to delete all the items in the input array those matches the if condition?

Thanks everyone

Simone Rossaini · Accepted Answer · 2022-09-23 11:35:41Z

2

You can use array_count_values with array_filter too like:

$input_array = array(
    "192.168.1.100",
    "192.168.1.101",
    "192.168.1.100",
    "192.168.1.102",
    "192.168.1.103",
    "192.168.1.198",
    "192.168.1.101",
    "192.168.1.25",
    "192.168.1.109",
    "192.168.1.109",
    "192.168.1.109",
    "192.168.1.100",
    "192.168.1.58"
);
$ipsCount = array_count_values($input_array);
$final_array = array_filter($input_array, function($val) use($ipsCount) {
    if($ipsCount[$val] >= 3){
        echo "IP $val  will be banned!" . PHP_EOL;
        return $val;
    }
});
print_r($final_array);

Reference:

You can extend same method for find value < 3

answered Sep 23, 2022 at 11:35

Simone Rossaini

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1 Comment

Tommy89 Over a year ago

I will deepen this solution, very cool!

RiggsFolly · Accepted Answer · 2022-09-23 15:13:43Z

1

Yes, add a key to the initial foreach and use it to unset the value in the input array you are adding to the ban list.

$input_array = array( "192.168.1.100", "192.168.1.101", "192.168.1.100", 
                        "192.168.1.102", "192.168.1.103", "192.168.1.198", 
                        "192.168.1.101", "192.168.1.25", "192.168.1.109", 
                        "192.168.1.109", "192.168.1.109", "192.168.1.100", 
                        "192.168.1.58") ;

$final_array = array();

$counted = array_count_values($input_array);
arsort($counted);   //get the big numbers first
foreach( $counted as $ip=>$cnt ){
    if ( $cnt >= 3 ) {
        $final_array[] = $ip;
        echo "IP $ip  will be banned!" . PHP_EOL;
    } else {
        break;  // stop unnecessary loops once we processed all the >= 3's
    }
}
//tidy the input array
$input_array = array_values(array_diff($input_array,$final_array));

edited Sep 23, 2022 at 15:13

answered Sep 23, 2022 at 11:18

RiggsFolly

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2 Comments

Tommy89 Over a year ago

Ok, this actually works. I don't get why it is working btw. The key 0 will be the first to be unset by unset($input_array[0]) because the first IP is listed 3 times in the array. But how can unset($input_array[0]) delete also key 2 and key 11?

RiggsFolly Over a year ago

Actually it didn't work when I looked closer! So I rewrote it, seems abit like the other answer now, purely a coinsidence, I didnt see that untill I posted this correction

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