Array search multiple values in consecutive order - php

Question

Take the given arrays:
// Original
array:14 [
0 => "hello"
1 => "i"
2 => "like"
3 => "cats"
4 => "they're"
5 => "cute"
6 => "and"
7 => "cuddly"
8 => "you"
9 => "know"
10 => "well"
11 => "i"
12 => "love"
13 => "cats"
]
// Sliced
array:6 [
0 => "like"
1 => "cats"
2 => "they're"
3 => "cute"
4 => "and"
5 => "cuddly"
]
I want to check the original array for my sliced values and retrieve their original keys. This must occur only when consecutive values match.
Ultimately, something like:
return array_keys_from_consec_values($original, $sliced);
// Result
array:14 [
0 => 2
1 => 3
2 => 4
3 => 5
4 => 6
5 => 7
]
Notes
sliced is not a result of using array_slice() on the original array. Otherwise I would have used that function and utilised the preserve keys parameter.
Want to avoid ambiguities. For example, a simple array_search for cats would return the key 3, but 13 also exists. Which might throw the function off.
In the event of any of the sliced values not existing in original (in order) an empty array should be returned. An example of a sliced array that would fail:
// Sliced
array:6 [
0 => "like"
1 => "cats"
2 => "they're"
3 => "cut3"
4 => "and"
5 => "cuddly"
]
Any recommendations, got speed in mind...

Answer 1

From what I understood, you want to get the index from the $original array based on values in $slice, you can use the array_flip() and the array_unique() functions:
function array_keys_from_consec_values($original, $slice){
// Get rid of duplicates and flip the keys with the values
$index = array_unique($original);
$index = array_flip($index);
$result = [];
// Loop through the slice
foreach($slice as $key => $value){
// Check if the value exists in the indexed array
if(!isset($index[$value])){
// Return an empty array
return array();
}
// And get the key from the flipped array
$result[$key] = $index[$value];
}
return $result;
}
var_dump(array_keys_from_consec_values($original, $slice));
This will give:
array (size=6)
0 => int 2
1 => int 3
2 => int 4
3 => int 5
4 => int 6
5 => int 7

Answer 2

This works on your example data and may be good enough:
$r = array_keys(array_unique(array_intersect($o, $s)));
If not, since you have a slice:
if(($k = array_search($s[0], $o)) === false ||
array_values($r = array_slice($o, $k, count($s), true)) != $s) {
$r = [];
}
Find the first key of the original from the first value of the slice
Slice from the original (preserving keys) and compare to the slice
For your example this yields:
Array
(
[2] => like
[3] => cats
[4] => they're
[5] => cute
[6] => and
[7] => cuddly
)
I see after the fact that you want to get the keys:
$r = array_values(array_flip($r));
If the slice is an actual array_slice from the original then pass true as the forth parameter to preserve the keys.

Answer 3

Good effort people, I admit the request was slightly hard to explain - so didn't get exactly what I was looking for. I realised that what I wanted was essentially an array_search that returns multiple keys when the needles are found consecutively. I've gone ahead and made the function myself:
/**
* Search for consecutive needles in haystack and return the corresponding keys.
*
* #param array $needles => Array values.
* #param array $haystack => Array to search.
* #param int $searchDirection => [0] (forwards) | [1] (backwards).
* #return array
*/
function array_search_all_consec(array $needles, array $haystack, $searchDirection = 0)
{
$needlesInScope = array_values($needles); // Keys not relevant, reset them.
$haystackInScope = $haystack;
if (in_array(reset($needlesInScope), $keys = array_keys($haystackInScope))) {
$needlesLength = count($needlesInScope);
foreach (($searchDirection == 0 ? $keys : array_reverse($keys)) as $offset) {
$length = $offset + $needlesLength;
$sliced = array_slice($haystackInScope, $offset, $length);
if (empty(array_diff_assoc($needlesInScope, $sliced))) {
return range($offset, $length - 1);
}
}
}
return [];
}
Test 1
$o = [
0 => "hello",
1 => "i",
2 => "like",
3 => "cats",
4 => "they",
5 => "cute",
6 => "and",
7 => "cuddly",
8 => "you",
9 => "know",
10 => "well",
11 => "i",
12 => "love",
13 => "cats",
];
$s = [
"i",
"love",
"cats",
];
return array_search_all_consec($s, $o);
// Result
array(3) {
[0] =>
int(11)
[1] =>
int(12)
[2] =>
int(13)
}
Test 2
$s = [
"i",
"like",
"cats",
];
return array_search_all_consec($s, $o);
// Result
array(3) {
[0] =>
int(1)
[1] =>
int(2)
[2] =>
int(3)
}
Test 3
$s = [
"i",
"lov3",
"cats",
];
return array_search_all_consec($s, $o);
// Result
array(0) {
}
Test 4
$s = [
"cats",
"i",
"love",
];
return array_search_all_consec($s, $o);
// Result
array(0) {
}
Test 5
$s = [
"i",
"love",
"cats",
"blah",
];
return array_search_all_consec($s, $o);
// Result
array(0) {
}
So there you have it. If anyone can improve the efficiency of the function please do contribute!