php pushing pattern from array1 to array2 - php

Question

I have an array that looks something like this
array(7) {
[0]=> "hello,pat1"
[1]=> "hello,pat1"
[2]=> "test,pat2"
[3]=> "test,pat2"
[4]=> "foo,pat3"
[5]=> "foo,pat3"
[6]=> "foo,pat3"
....
}
I would like to push it into another array so the output of the array2 is as follow:
array(7) {
[0]=> "hello,pat1"
[1]=> "test,pat2"
[2]=> "foo,pat3"
[3]=> "foo,pat3"
[4]=> "foo,pat3"
[5]=> "hello,pat1"
[6]=> "test,pat2"
.....
}
What I want is to push them in the following pattern: 1 "pat1" 1 "pat2" and 3 "pat3", and repeat this pattern every 5 elements.
while ( !empty( $array1 ) )
$a = explode(",",$array1[$i]);
if($a[1]=='pat1' &&)
push && unset
elseif($a[1]=='pat2' &&)
push && unset
elseif($a[1]=='pat3' and < 5)
push && unset and reset pattern counter
}
What would be a good way of doing this?
Any idea will be appreciate it.

Answer 1

Time for some fun with the iterators of the Standard PHP Library :-)
<?php
$array1 = array (
"hello1,pat1", "hello2,pat1", "hello3,pat1",
"test1,pat2", "test2,pat2",
"foo1,pat3", "foo2,pat3", "foo3,pat3",
"foo4,pat3", "foo5,pat3", "foo6,pat3"
);
// "group by" patN
$foo = array();
foreach($array1 as $a) {
// feel free to complain about the # here ...to somebody else
#$foo[ strrchr($a, ',') ][] = $a;
}
// split pat3 into chunks of 3
$foo[',pat3'] = array_chunk($foo[',pat3'], 3);
// add all "groups" to a MultipleIterator
$mi = new MultipleIterator(MultipleIterator::MIT_NEED_ANY);
foreach($foo as $x) {
$mi->attachIterator( new ArrayIterator($x) );
}
// each call to $mi->current() will return an array
// with the current items of all registered iterators
foreach ($mi as $x) {
// "flatten" the nested arrays
foreach( new RecursiveIteratorIterator(new RecursiveArrayIterator($x)) as $e) {
echo $e, "\n";
}
echo "----\n";
}

Answer 2

I think I'd set respective counters with respective incrementation. Since php will cast float keys to integers, you can just increment the ,pat3 items with .33 instead of 1. Then, to flatten the result, just use array_merge() with the splat operator.
Code: (Demo)
$array = [
"hello1,pat1",
"hello2,pat1",
"test3,pat2",
"test4,pat2",
"foo5,pat3",
"foo6,pat3",
"foo7,pat3",
];
$counters = [',pat1' => 0, ',pat2' => 0, ',pat3' => 0];
foreach ($array as $value) {
$end = strrchr($value, ',');
$groups[$counters[$end]][] = $value;
$counters[$end] += ($end === ',pat3' ? .33 : 1);
}
var_export(array_merge(...$groups));
Output:
array (
0 => 'hello1,pat1',
1 => 'test3,pat2',
2 => 'foo5,pat3',
3 => 'foo6,pat3',
4 => 'foo7,pat3',
5 => 'hello2,pat1',
6 => 'test4,pat2',
)