[kentoh]

I have a function that I want the closet array to be giving the best "rating" percentage. I have came across this:

Code:

$user = array(1,2,3,4,5);
$us = array(1,2,3,4,5,6);
$us1 = array(1,2,3,4,5);

$count = array_count_values(array_merge($user,$us));
foreach($count as $k => $v) {
 if($v > 1) {
   $hits = $hits + 1;
 
 }
}


echo $hits;

$counter = count($user);
print $counter;
print "<p>percentage: ". $hits / $counter;

I want the $us1 array to be the best matching since it completely matches the $user array.

SO when I put a percentage together they both come back as 100% match. Can someone please help me come up with an idea to make this work. The actual data comes from a mysql database and compares about 10 different arrays to one another and compares them for the best match.

Any and all help is greatly appreciated and thank you in advance.

[Keith]

Seems like a fair enough challenge. I have a solution that may work for you, but I have a quick question first: how would you like it to treat the following two arrays:

PHP Code:

$arr1 = array( 1, 2, 3, 4, 5 );
$arr2 = array( 1, 2, 3, 4, 5, 5 ); 

You'll notice the second has two values of 5. Should they be considered a 100% match?

[kentoh]

The arrays would never have the same number in them, each number represents a different feature that is a check box.

[Keith]

Give this a shot and see how it works out for you. I've attempted to comment it the best I can. It returns a float value between 0 and 1, 0 being 0% match, and 1 being 100% match.

PHP Code:

function array_cmp( Array $array_one, Array $array_two )
{

    // If both are empty, they are identical!
    if ( empty( $array_one ) && empty( $array_two ) )
    {
        return 1.;
    }

    // Ensure unique values only!
    $array_one = array_unique( $array_one );
    $array_two = array_unique( $array_two );

    // Count the two array values
    $count_one = count( $array_one );
    $count_two = count( $array_two );

    // Calculate their intersection
    $array_int = array_intersect( $array_one, $array_two );

    // Count their intersection
    $count_int = count( $array_int );

    // If no intersection, they are nothing alike...
    if ( 0 === $count_int )
    {
        return 0.;
    }

    // ...but if the intersection count matches both, they are identical!
    elseif ( $count_int === $count_one && $count_int === $count_two )
    {
        return 1.;
    }

    // Which is larger? We'd like to subtract the smaller from the larger
    switch ( TRUE )
    {
        // array one was larger
        case ( $count_one > $count_two ):
            $count_cmp  = $count_one;
            $difference = ( $count_one - $count_two );
            break;
        // array two was larger
        case ( $count_two > $count_one ):
            $count_cmp  = $count_two;
            $difference = ( $count_two - $count_one );
            break;
        // they must then be the same size
        default:
            $count_cmp  = $count_one;
            $difference = 0;

    }

    // Divide the difference by the larger count
    // - this will always be a float between `0` and `1`
    // - the further apart the array values, the higher the decimal value
    // - this is backward, so we correct this by subtracting from 1
    // - we then round to the nearest 100th decimal place
    return round( 1. - floatval( $difference / $count_cmp ), 2 );

} 

Usage:

PHP Code:

$arr1 = array();
$arr2 = array();
var_dump( array_cmp( $arr1, $arr2 ) ); // float(1)

$arr1 = array();
$arr2 = array( 1 );
var_dump( array_cmp( $arr1, $arr2 ) ); // float(0)

$arr1 = array( 1, 2, 3, 4, 5 );
$arr2 = array( 1, 2, 3, 4, 5 );
var_dump( array_cmp( $arr1, $arr2 ) ); // float(1)

$arr1 = array( 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 );
$arr2 = array( 1, 2, 3, 4, 5 );
var_dump( array_cmp( $arr1, $arr2 ) ); // float(0.5)

$arr1 = array( 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 );
$arr2 = array( 1, 2, 3, 4, 5, 6, 7, 8, 9 );
var_dump( array_cmp( $arr1, $arr2 ) ); // float(0.69) 

I hope this works out for you, or is at least a good start.