I have an array with multiple elements. I want to keep only the 10 most recent values. So I am reversing the array in a loop, checking if the element is within the first 10 range and if not, I unset the element from the array.
Only problem is that the unset does not work. I am using the key to unset the element, but somehow this does not work. The array keeps on growing. Any ideas?
$currentitem = rand(0,100);
$lastproducts = unserialize($_COOKIE['lastproducts']);
$count = 0;
foreach(array_reverse($lastproducts) as $key => $lastproduct) {
if ($count <= 10) {
echo "item[$key]: $lastproduct <BR>";
}
else {
echo "Too many elements. Unsetting item[$key] with value $lastproduct <BR>";
unset($lastproducts[$key]);
}
$count = $count + 1;
}
array_push($lastproducts, $currentitem);
setcookie('lastproducts', serialize($lastproducts), time()+3600);
I'd use array_slice ( http://php.net/array_slice ) perhaps like:
$lastproducts = unserialize($_COOKIE['lastproducts']);
// add on the end ...
$lastproducts[] = $newproduct;
// start at -10 from the end, give me 10 at most
$lastproducts = array_slice($lastproducts, -10);
// ....
You can use array_splice($input, $offset) function for this purpose.
$last_items_count = 10;
if(count($lastproducts) >= $last_items_count) {
$lastproducts = array_splice($lastproducts, count($lastproducts) - $last_items_count);
}
var_dump($lastproducts);
I hope this code helps.
For more information, here is the documentation:
http://php.net/manual/en/function.array-splice.php
I think a better way to select last 10 is:
$selection = array();
foreach(array_reverse($lastproducts) as $key => $lastproduct) {
$selection[$key] = $lastproduct;
if (count($selection)>=10) break;
}
Finally, $selection will have last 10 (or less) products.
Works great using array_splice and array_slice, thanks! :)
$lastproducts = unserialize($_COOKIE['lastproducts']);
// remove this product from array
$lastproducts = array_diff($lastproducts, array($productid));
// insert product on first position in array
array_splice($lastproducts, 0, 0, $productid);
// keep only first 15 products of array
$lastproducts = array_slice($lastproducts, 0, 15);
Related
I'm using the following code to retrieve the highest 3 numbers from an array.
$a = array(1,2,5,10,15,20,10,15);
arsort($a, SORT_NUMERIC);
$highest = array_slice($a, 0, 3);
This code correctly gives me the highest three numbers array(20,15,10); however, I'm interested in getting the highest 3 numbers including the ones that are identical. In this example, I'm expecting to get an array like array(10, 10, 15, 15, 20)
Might be simpler but my brain is tired. Use arsort() to get the highest first, count the values to get unique keys with their count and slice the first 3 (make sure to pass true to preserve keys):
arsort($a, SORT_NUMERIC);
$counts = array_slice(array_count_values($a), 0, 3, true);
Then loop those 3 and fill an array with the number value the number of times it was counted and merge with the previous result:
$highest = array();
foreach($counts as $value => $count) {
$highest = array_merge($highest, array_fill(0, $count, $value));
}
You can use a function like this:
$a = array(1,2,5,10,15,20,10,15); //-- Original Array
function get3highest($a){
$h = array(); //-- highest
if(count($a) >= 3){ //-- Checking length
$c = 0; //-- Counter
while ($c < 3 || in_array($a[count($a)-1],$h) ){ //-- 3 elements or repeated value
$max = array_pop($a);
if(!in_array($max,$h)){
++$c;
}
$h[] = $max;
}
sort($h); //-- sorting
}
return $h; //-- values
}
print_r(get3Highest($a));
Of course you can improve this function to accept a dinamic value of "highest" values.
The below function may be usefull
$a = array(1,2,5,10,15,20,10,15);
function getMaxValue($array,$n){
$max_array = array(); // array to store all the max values
for($i=0;$i<$n;$i++){ // loop to get number of highest values
$keys = array_keys($array,max($array)); // get keys
if(is_array($keys)){ // if keys is array
foreach($keys as $v){ // loop array
$max_array[]=$array[$v]; // set values to max_array
unset($array[$v]); // unset the keys to get next max value
}
}else{ // if not array
$max_array[]=$array[$keys]; // set values to max_array
unset($array[$keys]); // unset the keys to get next max value
}
}
return $max_array;
}
$g = getMaxValue($a,3);
Out Put:
Array
(
[0] => 20
[1] => 15
[2] => 15
[3] => 10
[4] => 10
)
You can modify it to add conditions.
I thought of a couple of other possibilities.
First one:
Find the lowest of the top three values
$min = array_slice(array_unique($a, SORT_NUMERIC), -3)[0];
Filter out any lower values
$top3 = array_filter($a, function($x) use ($min) { return $x >= $min; });
Sort the result
sort($top3);
Advantages: less code
Disadvantages: less inefficient (sorts, iterates the entire array, sorts the result)
Second one:
Sort the array in reverse order
rsort($a);
Iterate the array, appending items to your result array until you've appended three distinct items.
$n = 0;
$prev = null;
$top = [];
foreach ($a as $x) {
if ($x != $prev) $n++;
if ($n > 3) break;
$top[] = $x;
$prev = $x;
}
Advantages: more efficient (sorts only once, iterates only as much as necessary)
Disadvantages: more code
This gives the results in descending order. You can optionally use array_unshift($top, $x) instead of $top[] = $x; to get it in ascending order, but I think I've read that array_unshift is less efficient because it reindexes the array after each addition, so if optimization is important it would probably be better to just use $top[] = $x; and then iterate the result in reverse order.
i want to calculate two operations with the help of loop. They are already working and providing result i need. But i want them to look more like coding. So if anybody can help them with the help of for in php
for($i=0;i<something;$i++){
$temp_calc = ;
}
here are two statements.
In first statement length of array is 9.
In second statement length of array is 12.
both statements to be solved in different for loop as they are totally different questions.
$temp_calc = 10*$temp_array[0]+9*$temp_array[1]+8*$temp_array[2]+7*$temp_array[3]+6*$temp_array[4]+5*$temp_array[5]+4*$temp_array[6]+3*$temp_array[7]+2*$temp_array[8];
$temp_calc = 1*$temp_array[0]+3*$temp_array[1]+1*$temp_array[2]+3*$temp_array[3]+1*$temp_array[4]+3*$temp_array[5]+1*$temp_array[6]+3*$temp_array[7]+1*$temp_array[8]+3*$temp_array[9]+1*$temp_array[10]+3*$temp_array[11];
Thanks in advance
It will be a little simpler to use a foreach loop rather than a for loop. If you specifically need to use a for loop because it is a requirement of an assignment, you can check the PHP documentation. There are some examples there of using a for loop to loop over an array. This is a common and basic control structure and it will be more valuable for you to really understand how to use it. The more important part is what goes on inside the loop. There are multiple ways to do this, but here are some basic examples.
First one:
// initialize multiplier and result outside the loop
$multiplier = 10;
$result = 0;
// loop over the values
foreach ($temp_array as $value) {
// add the value * multiplier to the result and decrement the multiplier
$result += $value * $multiplier--;
}
Second one
// initialize multiplier and result outside the loop
$multiplier = 1;
$result = 0;
// loop over the values
foreach ($temp_array as $value) {
// add the value * multiplier to the result
$result += $value * $multiplier;
// switch the multiplier to the alternating value
if ($multiplier == 1) {
$multiplier = 3;
} else {
$multiplier = 1;
}
// The switch can be done more simply using a ternary operator like this:
// $multiplier = $multiplier == 1 ? 3 : 1;
}
for both issues:
$temp_array = array(2,2,2,2,2,2,2,2,2);//sample
function calc_1($temp_array){//first
$total=0;
$count = count($temp_array)+1;
foreach($temp_array as $value){
$total += $count*$value;
$count-=1;
}
return $total;
}
function calc_2($temp_array){//second
$total=0;
foreach($temp_array as $k=>$value){
$total += ($k%2==0) ? 1*$value : 3*$value;//when is even or odd
}
return $total;
}
var_dump(calc_1($temp_array));//resp1
var_dump(calc_2($temp_array));//resp2
If your array is called $myArray, then:
/*Since I can't know what the sequence of the values are that you
are multiplying, and because you might need other sequences in the
future, a function was developed that chooses which sequence you
want to multiply.*/
function findSomeValues($arraySize)
{
switch ($arraySize) {
case 9:
{
$someValues = array(10,9,8,7,4,5,4,3,2);
}
break;
case 12:
{
$someValues = array(1,3,1,3,1,3,1,3,1,3,1,3);
}
break;
default:
$someValues = array();
}
return $someValues;
}
/*This following function then finds how big your array is, looks
for a sequence stored in the findSomeValues function. If a sequence
exist for that array size (in this case if you have an array either
9 or 12 elements long), the result will be calculated and echoed. If
the sequence was not found, an error message would be echoed.*/
function multiplyValues($myArray) {
$result = 0;
$arraySize = count($myArray);//obtaining array size
$someValues = findSomeValues($arraySize);//obtaining sequence to multiply with
if (count($someValues)>0)
{
for($i=0;i<$arraySize;$i++){
$result += $myArray[i]*$someValues[i];
}
echo "result = ".$result."<br>";//result message
}
else
{
echo "you are missing some values<br>";//error message
}
}
Let me know if that worked for you.
Alternative:
If you prefer something a bit simpler:
//this array holds the sequences you have saved:
$sequenceArray = array(
9 => array(10,9,8,7,4,5,4,3,2),
12 => array(1,3,1,3,1,3,1,3,1,3,1,3)
);
//this function does the multiplication:
function multiplyValues($myArray)
{
$arraySize = count($myArray);
for($i=0;i<$arraySize;$i++){
$result += $myArray[i]*$sequenceArray[i];
}
echo "result = ".$result."<br>";//result message
}
For your result
$temp_calc = 10*$temp_array[0]+9*$temp_array[1]+8*$temp_array[2]+7*$temp_array[3]+6*$temp_array[4]+5*$temp_array[5]+4*$temp_array[6]+3*$temp_array[7]+2*$temp_array[8];
You should have for loop as following. It will run the loop till 8th index of your temp_array and multiply each index value with $i and sum up in a variable $temp_calc_1.
<?php
$temp_calc_1 = 0;
for($i=0;$i<9;$i++){
$temp_calc_1 = $temp_calc_1 + ( 10-$i)*$temp_array[$i] ;
}
For your second result
$temp_calc = 1*$temp_array[0]+3*$temp_array[1]+1*$temp_array[2]+3*$temp_array[3]+1*$temp_array[4]+3*$temp_array[5]+1*$temp_array[6]+3*$temp_array[7]+1*$temp_array[8]+3*$temp_array[9]+1*$temp_array[10]+3*$temp_array[11];
The above should be converted to the following loop, this will run loop till your 12th index of temparrayand do the calculation. This time it will multiply each index value of temparray by either 1 and 3. So first time it will multiply with 1 and next time with 3 and so on
//
$temp_calc_2 = 0;
for($i=0;$i<12;$i++){
$j = $i%2?3:1;
$temp_calc_2 = $temp_calc_2 + $j*$temp_array[$i] ;
}
?>
There is an array :
$ret = array();
... query execution
$ret['cnt'] = $this->db->num_rows(); // total number of database records
$i = 0;
while ( $this->db->next_record() ) { // fetching database records
$ret[$i]["user_id"] = $this->db->f('user_id') ;
$ret[$i]["user_login"] = stripslashes($this->db->f('user_login'));
$i++;
}
Now I want to remove from this array the element whose "user_id" is equal to a particular value :
if ($ret['cnt'] > 0) {
for ($i=0; $i<$ret['cnt']; $i++) {
if ($ret[$i]['user_id'] == $_SESSION[CODE_USER]) {
unset($ret[$i]);
break;
}
}
}
After printing the array I noticed that the element 0 is not in the array , this is what I am expecting. The only problem is now how to rearrange the array elements so that it will be compact again without any hole in its elements because the element 0 is not present ?
Use array_values:
$ret = array_values($ret);
http://php.net/manual/en/function.array-values.php
Or instead of using the 0th index. You could just grab the first element with reset.
http://php.net/manual/en/function.reset.php
array_values is probably the simplest way to reset keys.
if ($ret['cnt'] > 0) {
for ($i=0; $i<$ret['cnt']; $i++) {
if ($ret[$i]['user_id'] == $_SESSION[CODE_USER]) {
$ret = array_slice($ret,$i,1);
break;
}
}
}
array_slice will also strip away a section of the array and re-index as necessary.
this is my first php script and problem, I've searched hours with no conclusion other than looping a function" too many laterations". but it doesn't solve my problem I've never studied programming or what ever so I'm hoping that there is an educated person to fill me in on this:
I have an array that contains 120 elements; consists of duplicates eg:
myArray = [0]= item_1, [1] = item _1, [2] = item_2, [3] = item_3 ect..
Briefly I'm trying to make a flash php pokermachine but I need these items in the array to be shuffled BUT I do not want the duplicates to be next to each other after the shuffle but I need the duplicates to be still in the array
I can't do a loop function to check this because it will change the shuffle too many times which will effect the odds of the game: below is what I currently have:
/ * Removed the link here that is no longer available */
you may notice at times it will double up with 2 items in the same reel
Basically I created the virtual reel dynamically with php.ini file
these values are repeatedly pushed into an array($virtualreel) so the value may appear 10 times in the reel and another value will appear 5 times variating the odds. Then after I take a random slice() from the $virtualreel to display 3 vars from this reel and repeat the loop 4 more times for the other reels, also I only can shuffle once as I want the slice() to be from the same reels array order
I only shuffle every new spin not running loop functions to shuffle if I double up on a slice(array,3 items).
hope I've explained what I'm after well enough to give you guys an idea.
You can use this function:
<?php
function shuffleArray($myArray) {
$value_count = array_count_values($myArray);
foreach($value_count as $key=>$value) {
if ($value > count($myArray)/2) {
return false;
}
}
$last_value = $myArray[count($myArray) - 1];
unset($myArray[count($myArray) - 1]);
$shuffle = array();
$last = false;
while (count($myArray) > 0) {
$keys = array_keys($myArray);
$i = round(rand(0, count($keys) - 1));
while ($last === $myArray[$keys[$i]]) {
$i = round(rand(0, count($keys) - 1));
}
$shuffle[] = $myArray[$keys[$i]];
$last = $myArray[$keys[$i]];
unset($myArray[$keys[$i]]);
}
if ($last_value === $last) {
$i = 0;
foreach($shuffle as $key=>$value) {
if ($value !== $last_value) {
$i = $key;
break;
}
}
array_splice($shuffle, $i + 1, 0, $last_value);
} else {
$shuffle[] = $last_value;
}
return $shuffle;
}
print_r(shuffleArray(array(1,5,5,3,7,7)));
Why not just:
Edit :
$shuffled = array();
while(count($to_shuffle) > 0):
$i = rand(0, count($to_shuffle)-1);
$shuffled[] = $to_shuffle[$i];
array_splice($to_shuffle, $i, 1,null);
endwhile;
I think this is what you were expecting, if you don't mind not preserving the association between keys and values.
I have a database table with images that I need to display. In my view, I'd like to display UP TO 10 images for each result called up. I have set up an array with the 20 images that are available as a maximum for each result (some results will only have a few images, or even none at all). So I need a loop that tests to see if the array value is empty and if it is, to move onto the next value, until it gets 10 results, or it gets to the end of the array.
What I'm thinking I need to do is build myself a 2nd array out of the results of the test, and then use that array to execute a regular loop to display my images. Something like
<?php
$p=array($img1, $img2.....$img20);
for($i=0; $i<= count($p); $i++) {
if(!empty($i[$p])) {
...code
}
}
?>
How do I tell it to store the array values that aren't empty into a new array?
you could do something like:
$imgs = array(); $imgs_count = 0;
foreach ( $p as $img ) {
if ( !empty($img) ) {
$imgs[] = $img;
$imgs_count++;
}
if ( $imgs_count === 10 ) break;
}
You can simply call array_filter() to get only the non-empty elements from the array. array_filter() can take a callback function to determine what to remove, but in this case empty() will evaluate as FALSE and no callback is needed. Any value that evaluates empty() == TRUE will simply be removed.
$p=array($img1, $img2.....$img20);
$nonempty = array_filter($p);
// $nonempty contains only the non-empty elements.
// Now dow something with the non-empty array:
foreach ($nonempty as $value) {
something();
}
// Or use the first 10 values of $nonempty
// I don't like this solution much....
$i = 0;
foreach ($nonempty as $key=>$value) {
// do something with $nonempty[$key];
$i++;
if ($i >= 10) break;
}
// OR, it could be done with array_values() to make sequential array keys:
// This is a little nicer...
$nonempty = array_values($nonempty);
for ($i = 0; $i<10; $i++) {
// Bail out if we already read to the end...
if (!isset($nonempty[$i]) break;
// do something with $nonempty[$i]
}
$new_array[] = $p[$i];
Will store $p[$i] into the next element of $new_array (a.k.a array_push()).
Have you thought about limiting your results in the sql query?
select * from image where img != '' limit 10
This way you are always given up to 10 results that are not empty.
A ẁhile loop might be what you're looking for http://php.net/manual/en/control-structures.while.php