php array combinatorics/combination analyzes

Question

i need to discover all possible combinations for some arrays that have an specific char.

let me explain.

i have this text that have vectors organized as rows:

1342;-;+;V;+;-;V;V;V;ND;-;-;ND;ND;+;+;ND;-;ND;ND;ND;-;+;ND;+;-;-;-;ND;-;-;ND;ND;-;ND;ND;F;ND
2343;-;-;-;-;-;-;ND;-;ND;-;-;ND;ND;-;V;ND;V;ND;ND;ND;-;+;ND;-;-;-;V;ND;V;-;ND;ND;-;ND;ND;O;ND
2344;-;-;-;-;-;-;ND;-;ND;-;ND;ND;ND;ND;+;ND;+;ND;ND;ND;-;+;ND;+;-;-;-;ND;V;ND;ND;ND;-;ND;ND;O;ND
2345;-;V;V;+;V;V;ND;-;+;-;-;-;ND;-;V;ND;+;ND;V;ND;-;+;ND;-;-;-;-;V;-;+;ND;ND;-;-;+;F;-

each row is an vector..the attributes values are separeted by ";"

all possible values are: numbers, +, -, O, F, ND and 'V'
but the char V means + and -

what i need to to is to check for EACH ROW when the vector has in any attibute the char "V" because if have it means that this row must be replicated to all possibilities of V.

see this little example:

109 ; + ; - ; V ; ND ; +

i checked that this row has one or more than one "V" so now will calculate all possibilities that can be generated for this row

as we know V = + and - so this one row will generate:

109 ; + ; - ;  +  ; ND ; +
109 ; + ; - ;  -  ; ND ; +

as we have just one V so we will have 2 possibilities... the problem is when there is more than one 'V' .. how to calculate all combinations to it..

when creating the new text with all rows combinations the new text must not contain the origin row with the 'V'. note that all other attributes values remains the same.

thank you,

Greg · Accepted Answer · 2012-02-26 22:08:39Z

2

You can do it recursively. This solution assumes a limited dataset, where we wouldn't run the risk of exhausting memory.

<?php

$input = "5;V\n4;3";

$input_arr = explode("\n", $input);
foreach( $input_arr as $vector ){
    $output = replace_v(explode(';', $vector));
    foreach( $output as $output_line ){
        echo implode(';', $output_line) . "\n";
    }
}

function replace_v($input) {
    if( $key = array_search('V', $input) ){
        $a = $b = $input;
        $a[$key] = '-';
        $b[$key] = '+';
        return array_merge(replace_v($a), replace_v($b));
    }
    return array($input);
}

edited Feb 26, 2012 at 22:08

answered Feb 26, 2012 at 18:31

Greg

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4 Comments

Omnia Over a year ago

Hello Greg thank you, but i think there is some mistakes: Notice: Undefined variable: vector in C:\wamp\www\vector_v_combination\index.php on line 19 and Warning: array_search() expects parameter 2 to be array, null given in C:\wamp\www\vector_v_combination\index.php on line 19

Omnia Over a year ago

maybe because in the " function replace_v($input) { if( $key = array_search('V', $vector) ){ " .. $vector should be $input that's it ?

Omnia Over a year ago

even doing this it returns me the wrong answer: 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; + 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; + 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; + 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; + 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; + 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; + 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; + 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; + 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; + 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; + 109 ; + ; - ;-; ND ; + ;109 ; + ; - ;+; ND ; +

Omnia Over a year ago

Greg , thank you so much ! that's a great fucntion! good work ! thanks !

Collectives™ on Stack Overflow

php array combinatorics/combination analyzes

as we know V = + and - so this one row will generate:

as we have just one V so we will have 2 possibilities... the problem is when there is more than one 'V' .. how to calculate all combinations to it..

1 Answer 1

4 Comments

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Collectives™ on Stack Overflow

as we know V = + and - so this one row will generate:

as we have just one V so we will have 2 possibilities... the problem is when there is more than one 'V' .. how to calculate all combinations to it..

1 Answer 1

4 Comments

Your Answer

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