how to write a function for array manipulation? - php

Question

I need to create a logical relationships without inbreeding ...(animal crossing)
A B C D E
Each letter is below a family, which can vary from 2 to N (user input)
Array:
a b c d e f
Step 1 (print: )
ab bc cd de ef fa
Step 2 (print: )
abcd bcde cdef defa efab fabc
end there, because for example if you try to cross the abcd everyone else has at least one letter
SOME RULES
- The elements cannot be repeated at any stage eg: AA ou BB..CC..DD
- Elements of the groups may not be present in the next ... Example on the 3rd stage:
STRING: AB BC CD DE EA
WRONG -> AB BC
CORRECT -> AB CD
First stage, just print each element of array
Second Stage, print each element with the next, and the last with the first…
Three stage, print the 4 elements each family…
Any idea?
UPDATE
In my database i have an array:
eg:
["Fish1","FishEx3","FishExample","FishSpecie","FishOtherSpecie"]
I need use this function for parse this.

Answer 1

It's not a pretty solution but it works. PHP Fiddle
function Crossbreed($species = array())
{
if (empty($species)) {
return array();
}
$half_way = array();
$output = array();
$species_length = count($species) - 1;
foreach ($species as $index => $specie) {
$next = $index + 1;
if ($index >= $species_length) {
$next = $index - $species_length;
}
$half_way[] = $specie . $species[$next];
}
foreach ($half_way as $index => $specie) {
$next = $index + 2;
if ($next >= $species_length + 1) {
$next = $next - $species_length - 1;
}
$output[] = $specie . $half_way[$next];
}
return $output;
}
$species = array("Fish1","FishEx3","FishExample","FishSpecie","FishOtherSpecie");
$crossbred = Crossbreed($species);
Output of the $half_way variable (Did it with numbers in the array so its easy to read)
Array (
[0] => 12
[1] => 23
[2] => 34
[3] => 45
[4] => 56
[5] => 67
[6] => 78
[7] => 89
[8] => 91
)
Output of the function (Did it with numbers in the array so its easy to read)
Array (
[0] => 1234
[1] => 2345
[2] => 3456
[3] => 4567
[4] => 5678
[5] => 6789
[6] => 7891
[7] => 8912
[8] => 9123
)

Answer 2

Use this functions:
$arr = ['a', 'b', 'c', 'd', 'e', 'f'];
print_stage1($arr);
print_stage2($arr);
print_stage3($arr);
function increment($total, $pos, $inc){
if($pos + $inc < $total)
return $pos + $inc;
else
return ($pos + $inc) - $total;
}
function print_stage1($arr){
foreach($arr as $key => $family){
print $arr[$key]. " ";
}
}
function print_stage2($arr){
$total = count($arr);
foreach($arr as $key => $family){
$next_key = increment($total, $key, 1);
print $arr[$key] . $arr[$next_key]. " ";
}
}
function print_stage3($arr){
$total = count($arr);
foreach($arr as $key => $family){
$next1 = increment($total, $key, 1);
$next2 = increment($total, $key, 2);
$next3 = increment($total, $key, 3);
print $arr[$key] . $arr[$next1]. $arr[$next2]. $arr[$next3]. " ";
}
}

Answer 3

What you're explaining is a pretty simple unique combinatorics problem that can be solved with a stack. By shifting/popping one element at a time off the array/stack and concatenating it with another element you eventually exhaust your array. Repeat this as many times as you'd like for further combinatorics.
Here's an example.
function combine(Array $stack)
{
$newStack = [];
$lastElement = array_shift($stack);
while($nextElement = array_shift($stack)) { // shift
$newStack[] = $lastElement . $nextElement; // push
$lastElement = $nextElement;
}
return $newStack;
}
var_dump($level1 = combine(['a','b','c','d','e','f']), $level2 = combine($level1));
Result is ...
array(5) {
[0]=>
string(2) "ab"
[1]=>
string(2) "bc"
[2]=>
string(2) "cd"
[3]=>
string(2) "de"
[4]=>
string(2) "ef"
}
array(4) {
[0]=>
string(4) "abbc"
[1]=>
string(4) "bccd"
[2]=>
string(4) "cdde"
[3]=>
string(4) "deef"
}