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I have the following array with undefined number of elements
$marks=array('2','4','9','3');
target=50;
I want to randomly loop through the array, add up the values I fetch until the total is my target.
$total=0; /////initialize total
for($i=0;$i<=sizeof($marks);++$i)
{
/////////Pick up random values add them up until $total==$target
/////////return the new array with selected elements that sums up to
/////////target
}
I hope my question is clear, also note that the loop should not iterate too many times since the elements might never add up to the total. I have tried adding the items in line but to no avail. Thanks in advance
I think this'll work for you and always return you value of count to be 50 only
$marks = array(6,7,9,6,7,9,3,4,12,23,4,6,4,5,7,8,4);
$target = 50;
function sum($marks, $target) {
$count = 0;
$result = [];
for ($i = 0; $i <= $target; $i++) {
if ($count < $target) {
$add = $marks[array_rand($marks)];
$count = $count + $add;
$result['add'][] = $add;
} elseif ($count == $target) {
break;
} elseif ($count >= $target) {
$extra = $count - $target;
$count = $count-$extra;
$result['extra'] = $extra;
}
}
return $result;
}
print_r(sum($marks, $target));
The way you describe your logic, a while loop might make more sense:
<?php
$marks = array(2, 4, 9, 3);
$target = 50;
$sum = 0;
$i = 0; // to keep track of which iteration we're on
// PHP can natively randomize an array:
shuffle($marks);
while ($sum < $target && $i < count($marks)) {
$sum += $marks[$i];
$i++; // keep track of which iteration we're on
}
// after the loop, we've either added every number in $marks,
// or $sum >= $target
Don't forget that it might exceed $target without ever being equal to it, as Dagon pointed out in a comment.
Look into PHP's native array shuffle: https://secure.php.net/manual/en/function.shuffle.php
This may be a good alternative for the above answer.
Why I say so is that I have set it in such a way that it doesn't let the total go over the target, and when there is such a situation, the current number in the array is decremented by one and added as a new element so that if there is no possible number in the stack, there will be one eventually making this loop not go on infinitely. :)
<?php
$marks = ['2', '4', '9', '3'];
$target = 50;
$total = 0;
$numbersUsed = [];
while($total != $target) {
$index = rand(0, count($marks) - 1);
$number = $marks[$index];
if($number + $total > $target) {
$number = 0;
$marks[] = $marks[$index] - 1;
} else {
$numbersUsed[] = $number;
}
$total += $number;
echo $total . "\n";
}
// To see which numbers were used:
print_r($numbersUsed);
?>
Testing:
Starting with the array ['2', '4', '9', '3'],
We loop and get the result:
4 13 17 20 22 31 35 44 46 48 48 48 48 50
And we get this array which includes the numbers used to get the final result:
Array
(
[0] => 4
[1] => 9
[2] => 4
[3] => 3
[4] => 2
[5] => 9
[6] => 4
[7] => 9
[8] => 2
[9] => 2
[10] => 2
)
I am still a novice at PHP scripting.
I have an Array
$students = array(1201=>94,1203=>94,1200=>91, 1205=>89, 1209=>83, 1206=>65, 1202=>41, 1207=>38,1208=>37, 1204=>37,1210=>94);
From the associative array, the key are the student's exam no and the values are the student's scores. Then I used the 2 inbult PHP functions array_keys and array_values to separate the exam nos from the scores.
$exam_nos=(array_keys($students));
$marks=(array_values($students));
Then I passed the $marks array through the code below:
$i=0;
$occurrences = array_count_values($marks);
$marks = array_unique($marks);
echo '<table border="1">';
foreach($marks as $grade) {
if($grade == end($marks))$i += $occurrences[$grade]-1;
echo str_repeat('<tr><td>'.$grade.': '.($i+1).'</td></tr>',$occurrences[$grade]);
$i += $occurrences[$grade];
}
echo '</table><br />';
output:
94: 1
94: 1
94: 1
91: 4
89: 5
83: 6
65: 7
41: 8
38: 9
37: 11
37: 11
And this is closer to what I want; to rank the scores such that if a tie is encountered, 1 or more positions are skipped, occurs at the end the position the items at the end are assigned a position equivalent toi the total number of ranked items. However, it would be much helpful if this could be done without separating the Array into 2 ...
Questions:
(1) I am pulling my hair how, from the $student array I could have something like:
Exam No Score Position
1201 94 1
1210 94 1
1203 94 1
1200 91 4
1205 89 5
1209 83 6
1206 65 7
1202 41 8
1207 38 9
1204 37 11
1208 37 11
(2) I would like to be able to pick any student by exam no and be able to echo or print out her position e.g
the student 1207 is number 9.
I think I need to capture the postions in a variable, but how do I capture them? Well I don't know!
Could the experts help me here with a better way to achieve my 2 goals (please see questions 1 and 2)? I will try any suggestion that will help me disolve the 'metal blockage' I have hit.
If you're pulling out the students from a database (mentioned in the comments), you could retrieve them with the desired format directly using SQL.
However, I'm going to assume that that's not an option. You could do as follows:
$students = array(1201=>94,1203=>94,1200=>91, 1205=>89, 1209=>83, 1206=>65, 1202=>41, 1207=>38,1208=>37, 1204=>37,1210=>94);
arsort($students);// It orders high to low by value. You could avoid this with a simple ORDER BY clause in SQL.
$result = array();
$pos = $real_pos = 0;
$prev_score = -1;
foreach ($students as $exam_n => $score) {
$real_pos += 1;// Natural position.
$pos = ($prev_score != $score) ? $real_pos : $pos;// If I have same score, I have same position in ranking, otherwise, natural position.
$result[$exam_n] = array(
"score" => $score,
"position" => $pos,
"exam_no" => $exam_n
);
$prev_score = $score;// update last score.
}
$desired = 1207;
print_r($result);
echo "Student " . $result[$desired]["exam_no"] . ", position: " . $result[$desired]["position"] . " and score: ". $result[$desired]["score"];
Hope it helps you.
I would use a custom object to process the students individually and store them in an array.
$students = array(1201=>94,1203=>94,1200=>91, 1205=>89, 1209=>83, 1206=>65, 1202=>41, 1207=>38,1208=>37, 1204=>37,1210=>94);
arsort($students); // Sort the array so the higher scores are on top.
$newStudents = array();
$pos = 0;
$count = 0;
$holder = -1; // Assuming no negative scores.
foreach($students as $k=>$v){
$count++; // increment real counter
if($v < $holder || $holder == -1){
$holder = $v;
$pos = $count;
}
$newStudents[] = makeStudent($pos, $v, $k);
// If you want the exam # as the array key.
// $newStudents[$k] = $student;
}
$newStudents = fixLast($newStudents);
// outputs
print_r($newStudents);
foreach($newStudents as $v){
echo "position : " . $v->position . "<br>";
echo "score : " . $v->score . "<br>";
echo "exam : " . $v->exam . "<br>";
}
function makeStudent($pos, $score,$examNo){
$student = new stdClass(); // You could make a custom, but keeping it simple
$student->position = $pos;
$student->score = $score;
$student->exam = $examNo;
return $student;
}
function fixLast($students){
$length = count($students) -1;
$count = 0;
$i = $length;
while($students[$i]->position == $students[--$i]->position){
$count++;
}
for($i = 0; $i <= $count; $i++){
$students[$length - $i]->position = $students[$length - $i]->position + $count;
}
return $students;
}
<?php
function apache($b) {
return $b;
}
$a = array(1, 2, 3, 4, 5, 6);
$num = "";
foreach ($a as $b) {
$num = apache($b) . $num ;
}
echo $num;
?>
When you write it like this the output is 654321, but if you write it like this:
$num = $num . apache($b);
the output would be 123456. I don't understand why the results are like that. Can someone explain this?
This isn't really hard to understand.
This line:
$num = apache($b) . $num;
add the currently selected number and appends the current value of $num to it. The result will be written to $num.
So this will happen:
$b. $num = $num
1 . "" = 1
2 . 1 = 21
3 . 21 = 321
4 . 321 = 4321
5 . 4321 = 54321
6 . 54321 = 654321
If you write
$num = $num . apache($b);
instead, you're adding the currently selected number behind $num:
$num .$b = $num
"" . 1 = 1
1 . 2 = 12
12 . 3 = 123
123 . 4 = 1234
1234 . 5 = 12345
12345 . 6 = 123456
one way you are appending to the string
the other way you are prepending to the string
which gives the effect of reversing it.
first way kind of looks like this
[1]
2[1]
3[21]
4[321]
5[4321]
6[54321]
the other way looks like this
[1]
[1]2
[12]3
[123]4
[1234]5
[12345]6
where the value outside the [] is the value being returned by your function and the value inside the [] is $num
I have the following array
$example=array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16);
$limit=4 // 4 at the beginning only...
//it used to get incremented automatically to 8,12,16....
At first i want 1,2,3,4as an output for which i have done
foreach($example as $eg)
{
if($eg>$limit)
continue;
}
and i am easily getting 1,2,3,4 at the first then 1,2,3,4,5,6,7,8 then1,2,3,4,5,6,7,8,9,10,11,12
But now i what i want is 1,2,3,4 at the very beginning then 5,6,7,8 then 9,10,11,12 lyk this... how can i get that???
please do help me... :)
AS the
foreach($example as $eg)
{
if($eg>$limit)
continue;
}
is returning only 1,2,3,4 at $limit=4 and 1,2,3,4,5,6,7,8 at $limit=8
i need 1,2,3,4 at $limit=4 and 5,6,7,8 at $limit=8
Have you tried using the helpful built-in functions?
array_chunk($example,$limit);
Alternatively, for more page-like behaviour:
$pagenum = 2; // change based on page
$offset = $pagenum * $limit;
array_slice($example,$offset,$limit);
You would first chunk the array so each chunk has 4 elements, then loop through each chunk:
To change the numbers shown depending on which group, you could do:
$group = $_GET['group'];
$items = array_chunk($example, ceil(count($example)/4)[$group-1];
echo implode(", ", $items);
Then you can go to
yoursite.com/page.php?group=1
And it will output
1, 2, 3, 4
And when you go to
yoursite.com/page.php?group=2
It will output
5, 6, 7, 8
etc.
You can try something like this
$example=array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16);
$limit = 8;
$limit -= 4;
for($i = $limit; $i < ($limit + 4); $i++)
{
echo $example[$i].' ';
}
Output
//for $limit 4 output 1 2 3 4
//for $limit 8 output 5 6 7 8
//for $limit 16 output 13 14 15 16
I've got these two functions:
function drawNumber($drawnNumbers){
$unique = true;
while ($unique == true){
$number = mt_rand(10, 69);
if (!in_array($number, $drawnNumbers)){
return $number;
$unique = false;
}
}
}
fillCard(); ?>
It's a bingo game. The card gets filled with random Numbers. But I can't get it like this:
column column column column column column
row 10 13 16 14 16 19
row 24 26 28 29 23 21
row 36 33 39 30 31 35
row 46 48 42 45 43 47
row 59 56 51 52 58 50
row 60 65 68 62 61 67
So I would like to have the first row with numbers from 10 to 19
the second row from 20 to 29 and so on.
I tried like this
<?php drawnNumber(): $number = mt_rand(0,9);
fillArray(): $number = $row . $number; ?>
But that doesn't work, because there are double numbers in the card.
So before that I tried it in a different way,with in_array:
<?php
function fillCard(){
$card = array();
/* fill card with random numbers */
for($i = 0, $min = 10, $max = 19; $i < 6; $i++, $min+=10, $max += 10)
{
for($j = 0; $j < 6; $j++)
{
$number = mt_rand($min,$max) ;
if(!in_array($number, $card){
$card['row' . $i]['column' . $j]['number'] = $number;
$card['row' . $i]['column' . $j]['found'] = 0;
}
}
}
var_dump($card);
return $card;
} ?>
But there are still double random numbers in the card.
I tried a few other thinks in the last two weeks, but I just can't get it to work together.
If one thing succeeds the other thing fails.
I can get the random numbers but not unique random numbers in the card.
I hope someone can help me.
(for extra information: it's a bingo game. So drawnNumber() are the "balls", which get drawn
and stored in the array $drawnNumbers, they also are unique random numbers. fillCard() is the
function that fills the bingo card and checks if $drawNumber is in $card)
I would appreciate some help, if someone can tell me how to get it to work. Maybe in
an algorithm way or else some code?
Thank you in advance.
In general, you draw from some kind of box, right? So do the same, have an array with all available numbers and once you get a random number out of it, remove it, so the next time you search for a number, you will only pick from the remaining ones. Small example:
a[0] = 1
a[1] = 2
a[2] = 3
a[3] = 4
we pick a random number between 0 and 3 inclusive (0 and the length - 1 of a that is). Let's say we picked index 2, then a will look like:
a[0] = 1
a[1] = 2
a[2] = 4
Now if you draw a number between 0 and 2 (note that you take the length - 1 of a!), you won't re-pick the already chosen number in any way thus giving you unique numbers ALL the time.
P.S. this is a simplified version, but now if you can apply that to yourself and, for your example, create several arrays you will pick from.
The simplest way would be to have an additional flat array to keep track, and loop mt_rand
Here's an example of the meat of things:
$drawn = array();
// Loop around until you have a new number in the desired range
do {
$number = mt_rand($min,$max);
} while(in_array($number, $drawn));
// And save it to the $drawn array
$drawn[] = $rand;
To clarify, the above snippet (without the initialization of $drawn) is meant to replace the line
$number = mt_rand($min,$max) ;
in your code.
define('NB_ROWS', 6);
define('NB_COLS', 6);
$rows = range(10, NB_ROWS * 10, 10);
$bingo = array();
foreach($rows as $rowIndex)
{
$availNumbers = range(0, 9);
$line = array();
for($cellIndex = 0; $cellIndex < NB_COLS; $cellIndex++)
{
// pick a random value among remaining ones for current line
$numIndex = rand(0, count($availNumbers)-1);
list($value) = array_splice($availNumbers, $numIndex, 1);
$line[] = $value + $rowIndex;
}
$bingo[] = $line;
}
print_r($bingo);