Replacing Wildcards

[Drompo2]

Been trying to solve this problem for a while now, but have got nowhere.

 

If a user enters a string that contains certian ambigious characters, eg. Y, M, D

It replaces them with non-ambigious characters, this being a simple preg_replace function. But each letter (Y,M,D) has multiple non-ambigious characters, therefore could have several different combinations.

 

Any help at all very appreciated.

 

Ashley

[xyph]

You have to be more specific.

 

Give examples?

[Drompo2]

If a user entered string is ABYABM

 

and Y can mean A or B and M can be A, B or C

 

The string could be

ABAABA

ABBABA

ABAABB

ABBABB

ABAABC

ABBABC

[xyph]

This could get in to quite a few loops. Code coming up in a sec

[Drompo2]

Yeah i assumed it would contain many loops, check for each instance.

 

Thank you for your time

[xyph]

Here we go.

 

This is without recursion, AKA

 

Y = AB

M = XY therefor, M = XAB

 

Will not work. It can be done that way though.

 

<?php 

$spec = array(
'Y' => array('A','B'),
'M' => array('A','B','C')
);

$str = 'ABYABM';

$combos = getCombos( $str, $spec );

print_r( $combos );

function getCombos( $input, $special ) {

// $r will hold our final array to return
// str_split turns our string of letters into an array
$r = array(); $letters = str_split( $input );
// loop through each letter
foreach( $letters as $letter ) {
	// check to see if it's a special letter
	if( array_key_exists($letter,$special) ) {
		// if the first letter is special, we can just start $r with the
		// letters the special letter represents
		if( empty($r) ) $r = $special[$letter];
		// otherwise we'll have to rebuild $r
		else {
			// start off with a clean array
			$newR = array();
			// loop through each letter the special letter represents
			foreach( $special[$letter] as $specLetter )
				// then loop through each existing combination, appending the
				// current representative letter.
				foreach( $r as $return ) $newR[] = $return . $specLetter;
			// We then replace $r with our newly rebuilt version of it.
			$r = $newR;
		}
	// otherwise, it's not a special letter	
	} else {
		// if it's the first letter, we can start $r with it
		if( empty($r) ) $r[0] = $letter;
		// Otherwise, we have to loop through each existing combination and
		// append this letter to it
		else foreach( $r as $key => $return ) $r[$key] .= $letter;
	}

}

// Everything should be built. $r should have as many keys as the product of all
// amounts of special characters used. If you gave it a string like 'AYBYCMAB' you
// should have count(y) * count(y) * count(m) or 2*2*3 or 12 keys
return $r;

}

?>

 

Outputs

 

Array
(
    [0] => ABAABA
    [1] => ABBABA
    [2] => ABAABB
    [3] => ABBABB
    [4] => ABAABC
    [5] => ABBABC
)

 

Comments done

[Drompo2]

Works Perfectly, Thank you ever so much!

 

Been doing PHP for years and i couldnt get my head around this at all.

[xyph]

Loops inside loops can get ugly. I think it over step by step, and use a lot of echo's to help visualize what's happening to my strings, and what I want done to them.

 

If you're curious, I can show you the recursive version, for educational purposes. That's assuming you understand my code and what it does.

[Drompo2]

Yeah i understand your code, just trying to adapt it in to what i'm building, as the variables come in, in an array, using a forloop to seperate each one and then run your code to change the wildcards.

 

Is there anyway to add the combinations back on to the orignal array?

 

$string = $_POST["string"];
if ($string){ 
foreach ($string as $str){
$spec = array(
'Y' => array('A','B'),
'M' => array('A','B','C')
);

$combos = getCombos( $str, $spec);

print_r( $combos );

}
}

[Drompo2]

Managed to solve previous post.