Hi how can i optimize my code ?
$time_start = microtime(true);
$max = 2000;
$vx = [];
for ($i = 0; $i < $max; $i++) {
$vx[$i] = $i;
}
$vy = [];
for ($i = 0; $i < $max; $i++) {
$vy[$i] = $i;
}
$z = [];
$nb = 0;
foreach ($vx as $kx=>$x) {
foreach ($vy as $ky=>$y) {
$z[$x][$y] = cos($x*$x)-sin($y*-2);
$nb++;
}
}
$time_end = microtime(true);
echo ($time_end-$time_start).' microsec to process and calculate '.$nb.' z values';
And after this
$time_start = microtime(true);
$max = 2000;
$vx = [];
$vy = [];
for ($i = 0; $i < $max; $i++) {
$vx[$i] = $i;
$vy[$i] = $i;
}
$z = [];
$nb = 0;
foreach ($vx as $kx=>$x) {
foreach ($vy as $ky=>$y) {
$z[$x][$y] = cos($x*$x)-sin($y*-2);
$nb++;
}
}
$time_end = microtime(true);
echo ($time_end-$time_start).' microsec to process and calculate '.$nb.' z values';
The foreach loops are not necessary nor are the 2 arrays you build. It can all be done in 2 for loops like this
$max = 10;
$z = [];
for ($i = 0; $i < $max; $i++) {
for ($j = 0; $j < $max; $j++) {
$z[$i][$j] = cos($i*$i)-sin($j*-2);
}
}
print_r($z);
And after this
$time_start = microtime(true);
$max = 2000;
$vx = [];
$vy = [];
for ($i = 0; $i < $max; $i++) {
$vx[$i] = $i;
$vy[$i] = $i;
}
$z = [];
$nb = 0;
for ($i = 0; $i < $max; $i++) {
for ($j = 0; $j < $max; $j++) {
$z[$i][$j] = cos($i*$i)-sin($j*-2);
}
}
$time_end = microtime(true);
echo ($time_end-$time_start).' microsec to process and calculate '.$nb.' z values';```
can i optimise the double foreach ?
I'm trying to look for a number with maximum divisors in a range of 1 - 10000.
I succeeded, but then I wish to verify if there exist more than two max divisors and print them out. My array is really the problem. How can I clear an array and assign a new integer to it in an if else if statement?
Here is what I have tried:
function countDivisors(){
$input = 10000;
$maxNumOfDiv = -1;
$intWMaxDivs = -1;
$curNumOfDiv = 0;
$arr = array();
for($i=1; $i <= $input; $i++) {
$curNumOfDiv = 0;
for ($j = 1; $j < $i; $j++){
if ($i % $j == 0)
$curNumOfDiv++;
}
if($curNumOfDiv = $maxNumOfDiv){
$arr[] = $i;
$intWMaxDivs = $i;
$maxNumOfDiv = $curNumOfDiv;
} else if($curNumOfDiv > $maxNumOfDiv){
$arr = array();
$arr[] = $intWMaxDivs
$maxNumOfDiv = $curNumOfDiv;
}
}
for ($i; $i < count($arr); $i++){
echo $arr[$i]['intWMaxDivs'];
echo $arr[$i]['maxNumOfDiv'];
}
$div = [];
$maxDivKey = false;
$maxDiv = 0;
for($i = 1; $i <= 10000; $i++) {
for ($j = 1; $j < $i; $j++){
if ($i % $j == 0){
$div[$i][] = $i.'/'.$j.'='.$i/$j;
}
if($j == $i-1){
$count = count($div[$i]);
$div[$i]['count'] = $count;
if($maxDiv < $count){
$maxDiv = $count;
$maxDivKey = $i;
}
}
}
}
echo '<h1>Max divisors:</h1>';
print_r($div[$maxDivKey]);
//print_r($div);
I may be misunderstanding this question a little. If you are looking for a single number with maximum number of dividers, it should be something like this.
<?php
$max_num=10000;
$start_num=1;
$max_divs=-1;
$max_number=-1;
$numbers=array();
$max_divs_arr=array();
for($i=$start_num;$i<=$max_num;$i++)
{
$divs=0;
$div_array=array();
for($j=$start_num;$j<=$i;$j++)
{
if($i%$j==0)
{
$divs++;
$div_array[]=$j;
}
}
if($divs==$max_divs)
$max_divs_arr[$i]=$div_array;
if($divs>$max_divs)
{
$max_divs_arr=array();
$max_divs=$divs;
$max_divs_arr[$i]=$div_array;
}
}
foreach($max_divs_arr as $number=>$divisors)
echo "\nNumber with most divisors is $number\nIt has $max_divs divisors\nThose divisors are:".implode(',',$divisors);
Using the following code I can get the DCT of an image in PHP. Then I need to convert this back in to the compressed image. How can I achieve that?
<?php
$results = array();
$image1 = "baboon.jpg";
$ima = ImageCreateFromJPEG($image1);
$N1 = imagesx($ima);
$N2 = imagesy($ima);
$rows = array();
$row = array();
for ($j = 0; $j < $N2; $j++) {
for ($i = 0; $i < $N1; $i++)
$row[$i] = imagecolorat($ima, $i, $j);
$rows[$j] = dct1D($row);
}
for ($i = 0; $i < $N1; $i++) {
for ($j = 0; $j < $N2; $j++)
$col[$j] = $rows[$j][$i];
$results[$i] = dct1D($col);
}
print_r($results);
function dct1D($in) {
$results = array();
$N = count($in);
for ($k = 0; $k < $N; $k++) {
$sum = 0;
for ($n = 0; $n < $N; $n++) {
$sum += $in[$n] * cos($k * pi() * ($n + 0.5) / ($N));
}
$sum *= sqrt(2 / $N);
if ($k == 0) {
$sum *= 1 / sqrt(2);
}
$results[$k] = $sum;
}
return $results;
}
?>
Also I need to know how can I add some extra details like another message to this image too.. (image steganography). Please help. Thanks
I got this code to generate a list of 6 random products.
How can I make it generate each product inside a div?
$max_items = 6;
for($i = 0; $i < $max_items; $i++) {
echo $ps_product->show_snapshot($prodlist[$rand_prods[$i]], $show_price, $show_addtocart);
}
$max_items = 6;
for($i = 0; $i < $max_items; $i++) {
echo '<div>' . $ps_product->show_snapshot($prodlist[$rand_prods[$i]], $show_price, $show_addtocart) . '</div>';
}
$max_items = 6;
for($i = 0; $i < $max_items; $i++) {
printf('<div> %s </div>',$ps_product->show_snapshot($prodlist[$rand_prods[$i]], $show_price, $show_addtocart));
}
I wanted to have a way to get all combinations for all given numbers with given array length.
In my project the array size usually is 7. So I write a test code like this to see if I can get all needed combinations. The important part is every result array must be unique and maximum array size must be 7.
<?php
$numbers = [1, 2, 3, 4, 5, 6, 7];
$arraysize = 7;
$subset = [];
$count = count($numbers);
for ($i = 0; $i < $count; $i++) {
$subset[] = $numbers[$i];
}
for ($i=0; $i < $count; $i++) {
for ($j=$i; $j < $count; $j++) {
$subset[] = $numbers[$i] . $numbers[$j];
}
}
for ($i=0; $i < $count; $i++) {
for ($j=$i; $j < $count; $j++) {
for ($k=$j; $k < $count; $k++) {
$subset[] = $numbers[$i] . $numbers[$j] . $numbers[$k];
}
}
}
for ($i=0; $i < $count; $i++) {
for ($j=$i; $j < $count; $j++) {
for ($k=$j; $k < $count; $k++) {
for ($l=$k; $l < $count; $l++) {
$subset[] = $numbers[$i] . $numbers[$j] . $numbers[$k] . $numbers[$l];
}
}
}
}
for ($i=0; $i < $count; $i++) {
for ($j=$i; $j < $count; $j++) {
for ($k=$j; $k < $count; $k++) {
for ($l=$k; $l < $count; $l++) {
for ($m=$l; $m < $count; $m++) {
$subset[] = $numbers[$i] . $numbers[$j] . $numbers[$k] . $numbers[$l] . $numbers[$m];
}
}
}
}
}
for ($i=0; $i < $count; $i++) {
for ($j=$i; $j < $count; $j++) {
for ($k=$j; $k < $count; $k++) {
for ($l=$k; $l < $count; $l++) {
for ($m=$l; $m < $count; $m++) {
for ($n=$m; $n < $count; $n++) {
$subset[] = $numbers[$i] . $numbers[$j] . $numbers[$k] . $numbers[$l] . $numbers[$m] . $numbers[$n];
}
}
}
}
}
}
for ($i=0; $i < $count; $i++) {
for ($j=$i; $j < $count; $j++) {
for ($k=$j; $k < $count; $k++) {
for ($l=$k; $l < $count; $l++) {
for ($m=$l; $m < $count; $m++) {
for ($n=$m; $n < $count; $n++) {
for ($o=$n; $o < $count; $o++) {
$subset[] = $numbers[$i] . $numbers[$j] . $numbers[$k] . $numbers[$l] . $numbers[$m] . $numbers[$n] . $numbers[$o];
}
}
}
}
}
}
}
echo "<pre>";
print_r($subset);
echo "</pre>";
?>
When I run this code I get the combinations like I wanted (I make the combinations as string to see the results clearly but normally every result item in $subset array must be array)
With this code I can get all unique combinations.
But as you can see this code is ugly. I tried to make this a recursive function but I failed. Could anyone point me to right direction to get the exact same results like this? (every item in $subset array normally must be an array that contains digits)
You can simplify this logic (and make the code less ugly) without needing to go recursive by using:
for ($i = 0; $i < $count; $i++) {
$subset[] = $numbers[$i];
for ($j=$i; $j < $count; $j++) {
$subset[] = $numbers[$i] . $numbers[$j];
for ($k=$j; $k < $count; $k++) {
$subset[] = $numbers[$i] . $numbers[$j] . $numbers[$k];
for ($l=$k; $l < $count; $l++) {
$subset[] = $numbers[$i] . $numbers[$j] . $numbers[$k] . $numbers[$l];
}
}
}
}
the following will work in all cases even if you have duplicate numbers in your array
$array = array(1,2,3,4,5,6,7,8,9,10,11,12,13,14);
sort($array); //in case it 's not sorted
$array = array_slice($array,-7);
$num = count($array );
$total = pow(2, $num);
$result= array();
$element='';
for ($i = 0; $i < $total; $i++)
{
for ($j = 0; $j < $num; $j++)
{
if (pow(2, $j) & $i)
{
$element=$element.$array [$j];
}
}
$result[]=$element;
$element='';
}
print_r($result);
This implementation returns all the combinations of all items (77 = 823542 combinations of 7 items):
function combine_all(array $numbers) {
$count = count($numbers);
$result = array_map('strval', $numbers);
for($i = 1; $i < $count; ++$i) {
$combinations = array_slice($result, pow($count, $i-1));
foreach($numbers as $number) {
foreach($combinations as $combination) {
$result[] = $number . ',' . $combination;
}
}
}
return $result;
}
When using print_r to output the data, it can perform very slowly:
$array = array_fill(0, pow(7,7), '');
$t = microtime(true);
echo '<pre>';
print_r($array);
echo '</pre>';
echo microtime(true) - $t;
// 0.75329303741455
$t = microtime(true);
echo '<pre>';
print_r( combine_all(array(1,2,3,4,5,6,7)) );
echo '</pre>';
echo microtime(true) - $t;
// 1.7037351131439
$t = microtime(true);
combine_all(array(1,2,3,4,5,6,7));
echo microtime(true) - $t;
//0.75869607925415
To restrict the items number, use the array_slice function:
combine_all(array_slice($numbers, 0, 7));
If you really want a recursive function, you could do something like this:
function combine_all(array $numbers, $cnt=null, $baseCombination=null) {
if( $baseCombination === null ) {
$cnt = count($numbers);
}
if( $cnt > 0 ) {
$result = array();
foreach($numbers as $number) {
$combination = $number . ',' . $baseCombination;
$result[] = $combination;
$result = array_merge($result, combine_all($numbers, $cnt-1, $combination));
}
return $result;
}
return array();
}
But it takes too much memory.
I finally found out a way to add recursive function to create unique combinations from given numbers:
$numbers = [1, 2, 3, 4, 5, 6, 7];
function subsetSumRecursive($numbers, $arraySize, $level = 1, $i = 0, $addThis = [])
{
// If this is the last layer, use a different method to pass the number.
if ($level == $arraySize) {
$result = [];
for (; $i < count($numbers); $i++) {
$result[] = array_merge($addThis, array($numbers[$i]));
}
return $result;
}
$result = [];
$nextLevel = $level + 1;
for (; $i < count($numbers); $i++) {
// Add the data given from upper level to current iterated number and pass
// the new data to a deeper level.
$newAdd = array_merge($addThis, array($numbers[$i]));
$temp = subsetSumRecursive($numbers, $arraySize, $nextLevel, $i, $newAdd);
$result = array_merge($result, $temp);
}
return $result;
}
echo "<pre>";
print_r(subsetSumRecursive($numbers, 7));
echo "</pre>";