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I have an array. I'd like to get the three highest values of the array, but also remember which part of the array it was in.
For example, if my array is [12,3,7,19,24], my result should be values 24,19,12, at locations 4, 0, 3.
How do I do that? The first part is easy. Getting the locations is difficult.
Secondly, I'd like to also use the top three OR top number after three, if some are tied. So, for example, if I have [18,18,17,17,4], I'd like to display 18, 18, 17, and 17, at location 0,1,2,3.
Does that make sense? Is there an easy way to do that?
Wouldn't you be there using asort()?
For example:
<?php
$list = [4,18,18,17,17];
// Sort maintaining indexes.
asort($list);
// Slice the first 3 elements from the array.
$top3 = array_slice($list, -3, null, true);
// Results in: [ 1 => 18, 2 => 18, 3 => 17 ]
Or you can use arsort
function getMyTop($list, $offset, $top) {
arsort($list);
return array_slice($list, $offset, $top, true);
}
$myTop = getMyTop($list, 0, 3);
$myNextTop = getMyTop($list, 3, 4);
This is what you need!
<?php
$array = array(12,3,7,19,24);
$array_processed = array();
$highest_index = 0;
while($highest_index < 3)
{
$max = max($array);
$index = array_search($max,$array);
$array_processed[$index] = $max;
unset($array[$index]);
$highest_index++;
}
print_r($array_processed);
?>
You will get Index as well as the value! You just have to define how many top values you want! Let me know if it's what you want!
function top_three_positions($array){
// Sort the array from max to min
arsort($array);
// Unset everything in sorted array after the first three elements
$count = 0;
foreach($array as $key => $ar){
if($count > 2){
unset($array[$key]);
}
$count++;
}
// Return array with top 3 values with their indexes preserved.
return $array;
}
You can use a loop to determine how many elements your top-three-with-ties will have, after applying arsort:
function getTop($arr, $num = 3) {
arsort($arr);
foreach(array_values($arr) as $i => $v) {
if ($i >= $num && $v !== $prev) return array_slice($arr, 0, $i, true);
$prev = $v;
}
return $arr;
}
// Sample input
$arr = [4,18,17,6,17,18,9];
$top = getTop($arr, 3);
print_r($top); // [5 => 18, 1 => 18, 4 => 17, 2 => 17]
try this:
public function getTopSortedThree(array $data, $n = 3, $asc = true)
{
if ($asc) {
uasort($data, function ($a, $b) { return $a>$b;});
} else {
uasort($data, function ($a, $b) { return $a<$b;});
}
$count = 0;
$result = [];
foreach ($data as $key => $value) {
$result[] = $data[$key];
$count++;
if ($count >= $n){
break;
}
}
return $result;
}
Send false for desc order and nothing for asc order
Send $n with number of top values you want.
This functionality doesn't losing keys.
This task merely calls for a descending sort, retention of the top three values, and in the case of values after the third-positioned value being equal to the third value, retain these as well.
After calling rsort(), call a for() loop starting from the fourth element ([3]). If the current value is not equal to the value in the third position, stop iterating, and isolate the elements from the front of the array to the previous iteration's index. Done.
p.s. If the input array has 3 or fewer elements, the for() loop is never entered and the whole (short) array avoids truncation after being sorted.
Code: (Demo)
$array = [18, 17, 4, 18, 17, 16, 17];
rsort($array);
for ($i = 3, $count = count($array); $i < $count; ++$i) {
if ($array[2] != $array[$i]) {
$array = array_slice($array, 0, $i);
break;
}
}
var_export($array);
Because the loop purely finds the appropriate finishing point of the array ($i), this could also be compacted to: (Demo)
rsort($array);
for ($i = 3, $count = count($array); $i < $count && $array[2] === $array[$i]; ++$i);
var_export(array_slice($array, 0, $i));
Or slightly reduced further to: (Demo)
rsort($array);
for ($i = 3; isset($array[2], $array[$i]) && $array[2] === $array[$i]; ++$i);
var_export(array_slice($array, 0, $i));
Output:
array (
0 => 18,
1 => 18,
2 => 17,
3 => 17,
4 => 17,
)
Here is my problem:
I have an array with id's ($arr) which I'm slicing in groups of three. Next, I have an array with other id's ($otherIds) which I want to compare with main array ($arr), and if some of id's are identical - they should be deleted from rest of the $arr's chunks.
F.e. I have $arr = array(1, 2, 3, 4, 5, 6, 7, 8), and $otherIds = array(5, 7). I'm cutting $arr into the chunks of three elements, and then loop $arr in foreach and compare them to $otherIds, so in first iteration - code should see that $otherIds '5' and '7' exists in next chunks of $arr, and delete them.
My output should be:
1st iteration - array(1, 2, 3)
2nd iteration - array(4, 6) - 5 should be removed
3rd iteration - array(8) - 7 should be removed
$otherIds can be different in each iteration (they are taken from database), but to simplify it, I will use constant values.
Here is my code:
$arr = array(15, 10, 12, 17, 21, 13, 15, 25, 7, 18, 4, 1, 5, 2);
$chunks = array_chunk($arr, 3);
$ids = array();
foreach ($chunks as $k => $v) {
$otherIds = array(6, 7, 22, 31, 44, 9, 17);
$ids = $v;
foreach ($chunks as $key => $val) {
if ($key <= $k) continue;
foreach ($chunks[$key] as $g => $ch) {
foreach ($otherIds as $o) {
if ($ch['id'] == $o) {
$ids[] = $o;
unset($chunks[$key][$g]);
}
}
}
}
}
As You can see I use a lot of foreaches, but I cant see better solution...
Also, every next iteration of main foreach should be (as mentioned above) shortened by deleted elements from $otherIds - which I this code is NOT doing.
How to achieve it? Is there easier/better/more efficient solution?
I repeat: main goal is to check $otherIds in each iteration of main foreach, and delete same elements from $arr in other chunks.
When you modify an array you are iterating in a foreach loop, you mess up internal pointer in the array and things get confused.
Make a copy while picking up the triplets, do not do unset() nor modify the original array. Thanks to the copy-on-write feature in PHP, the copy will be fast and cost effective, even if the elements are big structures, not only numbers.
Try array_diff():
$arr = array(15, 10, 12, 17, 21, 13, 15, 25, 7, 18, 4, 1, 5, 2);
$chunks = array_chunk($arr, 3);
// Build the filtered list into $output
$output = array();
foreach ($chunks as $k => $v) {
$otherIds = array(6, 7, 22, 31, 44, 9, 17);
// array_diff() returns the list of values from $v that are not in $otherIds
$output[$k] = array_diff($v, $otherIds);
}
// Investigate the result
print_r($output);
Update
I re-read the question and I think I eventually understood the logic (which is not described in the sample data). On each iteration it gets a new set of IDs to ignore and removes them from all chunks, starting from the current chunk.
The updated code is:
$arr = array(15, 10, 12, 17, 21, 13, 15, 25, 7, 18, 4, 1, 5, 2);
$chunks = array_chunk($arr, 3);
// $chunks is numerically indexed; we can use for() to iterate it
// (avoid assigning to $v a value that is never used)
$count = count($chunks);
for ($k = 0; $k < $count; $k ++) {
$otherIds = array(6, 7, 22, 31, 44, 9, 17);
// $chunks is numerically indexed; start with key `$k` to iterate it
for ($key = $k; $key < $count; $key ++) {
// remove the values from $otherId present in the chunk
$chunks[$key] = array_diff($chunks[$key], $otherIds);
}
}
The values in this array are inserted by pulling XML values (using the simplexml_load_file method) and a foreach loop.
$skuArray(2, 4, 3, 7, 7, 4, 1, 7, 9);
After populating the array, I then need to check to see if any duplicate values exist in the array (IE, 7 and 4 in this case). Product->sku contains the skuArray value (from an XML file) in the foreach loop below. The code below isn't working. Any advice? Thanks!
foreach($XMLproducts->product as $Product) {
if (in_array($Product->sku, $skuArray, > 1) {
// execute code
}
}
Use array_count_values() to get the number of times a value occurs and then check to see if it is more than one
$skuArray = array(2, 4, 3, 7, 7, 4, 1, 7, 9);
$dupes = array_count_values($skuArray);
foreach($XMLproducts->product as $Product) {
if ($dupes[$Product->sku] > 1) {
// execute code
}
}
If you need to remove the duplicates then you can use array_unique:
<?php
$input = array(4, 4, 3, 4, 3, 3);
$result = array_unique($input);
// $result = array(4, 3)
?>
If you need only check if there are duplicates then you can do it using array_count_values:
<?php
$input = array(2, 4, 3, 7, 7, 4, 1, 7, 9);
$counts = array_count_values($input);
$duplicates = array();
foreach($counts as $v => $count){
if($count > 1)
$duplicates[] = $v;
}
Then you will have an array $duplicates with the duplicated values.
Source: Php check duplicate values in an array
Your code has typo:
if (in_array($Product->sku, $skuArray, > 1) {
in_array expect the first parameter the needle, but you mentioned "Product->sku contains the skuArray value ", anyway, it should be like this:
if (in_array($Product->sku, $skuArray)) {
In a PHP project I have some data I want to sort using a linear time, simple counting sort:
$ar = array(7, 2, 0, 3, 8, 0, 12, 7, 6, 7);
$count = array();
foreach ($ar as $v)
$count[$v]++;
$sorted = array();
foreach ($count as $v => $c)
for ($i = 0; $i < $c; $i++)
$sorted[] = $v;
The problem is that the above obviously doesn't work. The php array works more like a hashmap than an array. The code can be made to work by inserting ksort($count) before the final loop, but ksort runs in O(nlogn) which destroys the entire point.
Is there any way to do a linear time sort in php? Perhaps using some paramter to array(), or some entirely different structure?
You didn't follow the algorithm correctly. This is O(n).
$ar = array(7, 2, 0, 3, 8, 0, 12, 7, 6, 7);
$count = array();
foreach ($ar as $v) {
$count[$v] = isset($count[$v]) ? $count[$v] + 1 : 1;
}
$sorted = array();
$min = min($ar);
$max = max($ar);
for ($i=$min; $i<=$max; $i++) {
if (isset($count[$i])) {
for ($j=0; $j<$count[$i]; $j++) {
$sorted[] = $i;
}
}
}
also, see array_count_values(), or alternatively compute the min and max inside the counting loop.
Approved answer is wrong. Correct:
$ar = array(7, 2, 0, 3, 8, 0, 12, 7, 6, 7);
$count = array();
foreach ($ar as $v) {
$count[$v] = isset($count[$v]) ? $count[$v] + 1 : 1;
}
$sorted = array();
$min = min($ar);
$max = max($ar);
for ($i=$min; $i <= $max; $i++) {
if (isset($count[$i])) {
for ($j=0; $j<$count[$i]; $j++) {
$sorted[] = $i;
}
}
}
If i understand your question AND comment correctly, just using sort($count) would work no?
$ar = array(7, 2, 0, 3, 8, 0, 12, 7, 6, 7);
$sorted = $ar;
sort($sorted);
var_dump($ar);
var_dump($sorted);
Result:
array(7,2,0,3,8,0,12,7,6,7);
array(0,0,2,3,6,7,7,7,8,12);
But i'm wondering what the foreach($ar as $v)$count[$v]++; does... doesn't really make sense...
Adding some comments to the code to show you why this doesn't do what you think it should do.
$ar = array(7, 2, 0, 3, 8, 0, 12, 7, 6, 7);
$count = array();
foreach ($ar as $v) {
// add each number in $ar to $count.
// the first number in $ar is 7, so 7 will be the first number in $count.
// because 7 is in $ar 3 times, $count[7] == 3.
$count[$v]++;
}
// the output of print_r will be very revealing:
print_r($count);
/*Array
(
[7] => 3
[2] => 1
[0] => 2
[3] => 1
[8] => 1
[12] => 1
[6] => 1
)*/
$sorted = array();
foreach ($count as $v => $c) {
// the first entry: $count[7] == 3
// so add 7 to $sorted 3 times.
// the second entry: $count[2] == 1
// so add 2 to $sorted 1 time.
// etc.
for ($i = 0; $i < $c; $i++) {
$sorted[] = $v;
}
}
This simply groups numbers together based on their location in the first array.
To get the sorted $ar in a variable of it's own ($sorted), it's pretty trivial:
$sorted = $ar;
sort($sorted);
Which makes me think that your question and comment is not giving the whole picture.
Edit: Now after you have clarified that you wanted to implement a specific algorithm (and you actually got an answer already that shows some points that were wrong implementing it first), I think it's worth to focus on another aspect of your question:
You're comparing the complexity of two (theoretical) algorithms, but you're leaving aside how the algorithms are implemented.
PHP's sort() - even based on "bad" quicksort, will outrun your own PHP usercode implementation of some other algorithm by numbers.
You just have compared the wrong parameters here. The complexity of a function does not says much when you compare a build-in PHP function with some function in your user-code.
$A = [1, 2, 2, 2, 1, 3, 3, 1, 2, 4, 5, 0, 0]; // example array
$m = max($A);
$count = array_fill(0, $m + 1, '0');
foreach ($A as $value) $count[$value] += 1;
// next step is print the numbers
$a = [];
foreach ($count as $key => $value) {
for ($i = 0; $i < $value;) {
array_push($a, $key);;
$i++;
}
}
var_dump($count); // print the sorted array
var_dump($a); // print the numbers (low to high)
First of all, I'd like to point out to all you duplicate question hunters that this question does not fully answer my question.
Now, I've got an array. We'll say that the array is array(1, 2, 2, 3, 4, 3, 2)
I need to remove the duplicates. Not just one of the duplicates, but all, so that the result will be array(1, 4)
I looked at array_unique(), but that will only result in array(1, 2, 3, 4)
Any ideas?
You could use the combination of array_unique, array_diff_assoc and array_diff:
array_diff($arr, array_diff_assoc($arr, array_unique($arr)))
function removeDuplicates($array) {
$valueCount = array();
foreach ($array as $value) {
$valueCount[$value]++;
}
$return = array();
foreach ($valueCount as $value => $count) {
if ( $count == 1 ) {
$return[] = $value;
}
}
return $return;
}