How to retrieve repeating substrings from a string? [closed] - php

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how to explode even words in string of symbol "-"? for ex.:
$string = 'tshirt-blue-124-tshirt-blue-124-tshirt-blue-124';
or
$string = '333-red-333-red-333-red-333-red';
I need array like this:
$string[0] = 'tshirt-blue-124';
$string[1] = 'tshirt-blue-124';
$string[2] = 'tshirt-blue-124';
or
$string[0] = '333-red';
$string[1] = '333-red';
$string[2] = '333-red';
$string[3] = '333-red';
thanks

Answer 1

If it's always every three elements:
$string = 'tshirt-blue-124-tshirt-blue-124-tshirt-blue-124';
$newArray = array_chunk(explode('-', $string), 3);
array_walk(
$newArray,
function(&$value) {
$value = implode('-', $value);
});
var_dump($newArray);
EDIT
But you must know how many elements in advance:
$splitValue = 2;
$string = '333-red-333-red-333-red-333-red';
$newArray = array_chunk(explode('-', $string), $splitValue);
array_walk(
$newArray,
function(&$value) {
$value = implode('-', $value);
});
var_dump($newArray);
EDIT #2
If you have no idea how many elements that there in a repetition block, then look into the Lempel-Ziv-Welsh (LZW) compression algorithm. It is built on detecting repetitions in strings and utilizing them for compression. You can probably use a Suffix Trie datastructure to simplify the logic.
EDIT #3
As a simplistic approach to trying to identify the split size:
function getSplitSize($string) {
$splitSize = 2;
do {
$tempArray = array_chunk(explode('-', $string), $splitSize);
if ($tempArray[0] == $tempArray[1])
return $splitSize;
++$splitSize;
} while ($splitSize <= count($tempArray));
throw new Exception('No repetition found');
}
function splitStringOnRepetition($string) {
$newArray = array_chunk(explode('-', $string), getSplitSize($string));
array_walk(
$newArray,
function(&$value) {
$value = implode('-', $value);
}
);
return $newArray;
}
$string = 'tshirt-blue-124-tshirt-blue-124-tshirt-blue-124';
$array = splitStringOnRepetition($string);
var_dump($array);
$string = '333-red-333-red-333-red-333-red';
$array = splitStringOnRepetition($string);
var_dump($array);

Answer 2

For advanced yet efficient method, you can use a regular expression matching using preg_match():
$string = 'tshirt-blue-124-tshirt-blue-125-tshirt-blue-126';
$pattern = "/([A-Za-z]*-[A-Za-z]*-[\d]*)-?/";
preg_match_all($pattern, $string, $matches);
echo "<pre>";
print_r($matches[1]);
echo "</pre>";
and it will output:
Array
(
[0] => tshirt-blue-124
[1] => tshirt-blue-125
[2] => tshirt-blue-126
)
you can set the pattern the way you want..

Answer 3

Try with -
$string = 'tshirt-blue-124-tshirt-blue-124-tshirt-blue-124';
$new = explode('-', $string);
$i = 0;
$result = array();
while ($i < count($new)) {
$result[] = $new[$i].'-'.$new[$i+1].'-'.$new[$i+2];
$i += 3;
}
var_dump($result);

Answer 4

you can do something like this
$string = 'tshirt-blue-124-tshirt-blue-124-tshirt-blue-124';
$tmp = explode("-", $string);
while ($tmp) {
$output[] = implode('-', array_splice($tmp, 0, 3));
}
print_r($output);

Answer 5

Explode it
$string = explode("tshirt-", $string);
Now you have to add the value to each Array element
foreach($string as &$v){
$v = "tshirt-" . $v;
$v = rtrim($v, "-");
}
This is a very easy and simple to understand solution.