Related
Is there an efficient way to get an array by skipping every n elements starting from the end (so that the last element is always in the result)?
Basically, I have a large array of 300k elements that I want to turn to 100k or 150k.
Sample input:
$array = array(0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15);
Test: skip every other element
$x = 1;
Expected output:
$new_array = array(1,3,5,7,9,11,13,15);
Test: skip every second element
$x = 2;
Expected output:
$new_array = array(0,3,6,9,12,15);
Test: skip every third element
$x = 3;
Expected output:
$new_array = array(3,7,11,15);
Use a for() loop with a decrementing counter to allow you to push qualifying elements into the result array starting from the end of the array. To put the result array in the original order, just call array_reverse() after the loop.
Code: (Demo)
function skipFromBack(array $array, int $skip): array {
$result = [];
for ($index = array_key_last($array); $index > -1; $index -= 1 + $skip) {
$result[] = $array[$index];
}
return array_reverse($result);
}
Alternatively, you can pre-calculate the starting index, use an incrementing counter, and avoid the extra array_reverse() call. (Demo)
function skipFromBack(array $array, int $skip): array {
$increment = $skip + 1;
$count = count($array);
$start = ($count - 1) % $increment;
$result = [];
for ($i = $start; $i < $count; $i += $increment) {
$result[] = $array[$i];
}
return $result;
}
function skip_x_elements($array, $x)
{
$newArray = [];
$skipCount = 0;
foreach ($array as $value) {
if ($skipCount === $x) {
$newArray[] = $value;
$skipCount = 0;
} else {
$skipCount++;
}
}
return $newArray;
}
This should do what you want.
Improving upon #Dieter_Reinert answer, so you can also retain the keys inside said array, here is a slightly more flexible version that better fits the original question:
function skipX($array, $x, $grab = false){
$x = (!$grab) ? $x: $x - 1;
if($x <= 0) return $array;
$count = (count($array) % $x == 0) ? 0:$x;
$temparr = [];
foreach($array as $key => $value){
if($count === $x){
$temparr[$key] = $value;
$count = 0;
}else $count++;
}
return $temparr;
}
Example:
$array = range(0, 15);
foreach ([0, 1, 2, 3] as $skip){
print_r(skipX($array, $skip));
echo "\n---\n";
}
The correct output based on the original question:
Array
(
[0] => 0
[1] => 1
[2] => 2
[3] => 3
[4] => 4
[5] => 5
[6] => 6
[7] => 7
[8] => 8
[9] => 9
[10] => 10
[11] => 11
[12] => 12
[13] => 13
[14] => 14
[15] => 15
)
---
Array
(
[1] => 1
[3] => 3
[5] => 5
[7] => 7
[9] => 9
[11] => 11
[13] => 13
[15] => 15
)
---
Array
(
[2] => 2
[5] => 5
[8] => 8
[11] => 11
[14] => 14
)
---
Array
(
[0] => 0
[4] => 4
[8] => 8
[12] => 12
)
---
Online PHP Sandbox Demo: https://onlinephp.io/c/7db96
I have two arrays, Array 1 being a donor array which has a series of values (not necessarily equal values as in my example). Array 2 is the desired result and would store a series of sub arrays with values from Array 1 where each sub array's total sum would not exceed 25. If it does, the excess would get pushed to the next index in Array 2 where the rules would also apply.
Donor array (Array 1):
$a1=array(10,10,10,10,10,10,10,10,10,10);
Desired output (Array 2):
Array
(
[0] => 10,10,5
[1] => 5,10,10
[2] => 10,10,5
[3] => 5,10,10
)
Here the code I tried but it gets an error:
Notice: Undefined offset: 10...etc.
$a1=array(10,10,10,10,10,10,10,10,10,10);
$a2=array();
$count=count($a1);
for($i=0;$i<$count;$i++){
$a2count=array_sum($a2);
if($a2count>25){
$i=$i+1;
$a2[$i]=$a1[$i];
}
else{
$a2[$i]=$a1[$i];
}
}
print_r($a2);
I don't know what logic to implement and get result I'm looking for.
Mayhaps something like this will work for you. I will notate so it's not just a copy-and-paste answer. Maybe someone will get some insight on it to improve it in the future:
function slitArray($a1,$num = 25)
{
# Used to store the difference when the value exceeds the max
$store = 0;
# Storage container that will be built using sums/diffs
$new = array();
# Loop through the main array
foreach($a1 as $value) {
# If the last key/value pair in our return array is an array
if(is_array(end($new)))
# Add up the values in that array
$sum = array_sum(current($new));
else
# If not array, no values have been stored yet
$sum = 0;
# This just gets the last key
$count = (count($new)-1);
# Assign last key
$i = ($count <= 0)? 0 : $count;
# If the sum of the current storage array plus the value
# of the current array is greater than our max value
if(($sum + $value) > $num) {
# Take max and remove the current total of storage array
$use = ($num-$sum);
# Take what's left and remove it from the current value
$store = ($value-$use);
# If the current stored value (the value we want to push to
# the next storage k/v pair) is more than the max allowed
if($store > $num) {
# Takes a value, checks if it's greater than max,
# and if it is, breaks the value up by max as a divider
$divide = function($store,$num)
{
if($store > $num) {
$count = ceil($store/$num);
for($i=0; $i<$count; $i++) {
$new[] = ($store > $num)? $num : $store;
$store -= $num;
}
return $new;
}
else
return array($store);
};
# This should either be an array with 1 or more values
$forward = $divide($store,$num);
# Do a look forward and add this excess array into our
# current storage array
$a = $i;
foreach($forward as $aVal) {
$new[$a+=1][] = $aVal;
}
}
# If the store value is less than our max value, just add
# it to the next key in this storage array
else {
$new[$i+1][] = $store;
# Reset the storage back to 0, just incase
$store = 0;
}
}
# Set the current "use" value as the current value in our
# from-array. Since it doesn't exceed the max, it just gets
# added to the storage array
else
$use = $value;
# Sometimes the math makes $use 0, keep that out of the
# storage array. The $use value is the current value to add at
# the time of iteration. Previous storage values are added as
# future-keys
if($use > 0)
$new[$i][] = $use;
}
# Return the final assembled array
return $new;
}
# To use, add array into function
$a1 = array(10,10,10,10,10,10,10,10,10,10);
# to split using different max value, just add it to second arg
# example: slitArray($a1,20);
print_r(slitArray($a1));
Gives you:
Array
(
[0] => Array
(
[0] => 10
[1] => 10
[2] => 5
)
[1] => Array
(
[0] => 5
[1] => 10
[2] => 10
)
[2] => Array
(
[0] => 10
[1] => 10
[2] => 5
)
[3] => Array
(
[0] => 5
[1] => 10
[2] => 10
)
)
An array input of:
$a1 = array(23,2,71,23,50,2,3,4,1,2,50,75);
Gives you:
Array
(
[0] => Array
(
[0] => 23
[1] => 2
)
[1] => Array
(
[0] => 25
)
[2] => Array
(
[0] => 25
)
[3] => Array
(
[0] => 21
[1] => 4
)
[4] => Array
(
[0] => 19
[1] => 6
)
[5] => Array
(
[0] => 25
)
[6] => Array
(
[0] => 19
[1] => 2
[2] => 3
[3] => 1
)
[7] => Array
(
[0] => 3
[1] => 1
[2] => 2
[3] => 19
)
[8] => Array
(
[0] => 25
)
[9] => Array
(
[0] => 6
[1] => 19
)
[10] => Array
(
[0] => 25
)
[11] => Array
(
[0] => 25
)
[12] => Array
(
[0] => 6
)
)
Here you go: The logic is not so hard. Hope it helps.
<?php
$a1=array(10,10,10,10,10,10,10,10,10,10);
$a2 = [];
$a3 = [];
$m = 0;
for($i = 0; $i < count($a1); ++$i){
$m += $a1[$i];
if($m > 25){
$n = $m % 25;
if(array_sum($a2) != 25){
$a2[] = $n;
}
$a3[] = implode(',', $a2);
$a2 = [];
$m = $n;
$a2[] = $n;
} else{
$a2[] = $a1[$i];
}
}
$a3[] = implode(',', $a2);
print_r($a3);
?>
The final code for this question
<?php
function slitArray($a1,$num = 25)
{
$store = 0;
$new = array();
foreach($a1 as $value) {
if(is_array(end($new)))
$sum = array_sum(current($new));
else
$sum = 0;
$count = (count($new)-1);
$i = ($count <= 0)? 0 : $count;
if(($sum + $value) > $num) {
$use = ($num-$sum);
$store = ($value-$use);
if($store > $num) {
$divide = function($store,$num)
{
if($store > $num) {
$count = ceil($store/$num);
for($i=0; $i<$count; $i++) {
$new[] = ($store > $num)? $num : $store;
$store -= $num;
}
return $new;
}
else
return array($store);
};
$forward = $divide($store,$num);
$a = $i;
foreach($forward as $aVal) {
$new[$a+=1][] = $aVal;
}
}
else {
$new[$i+1][] = $store;
$store = 0;
}
}
else
$use = $value;
if($use > 0)
$new[$i][] = $use;
}
return $new;
}
$a1 = array(10,20,30,40,50,60);
$arr=slitArray($a1);
print_r($arr);
?>
Let me help you a bit using Pseudocode:
ar1 = {10,10,10,20,40,[0]=>1,[0]=>3,[0]=>4};
ar2 = new array (ar.length) \\ worst case
int c = 0; \\current
foreach (ar1 as $value){
ar2 [c]+=ar1[i];
if (ar2 [c]>25){ c++;}
}
Logic behind the code:
Add the value of ar1[i] to the current ar2 value till it passes your limit (25 in this case). If it exceeds you boundary, than move to the next value in the goal array. The worst case would be, that every value is over 25, so it would be an exact copy of the original array.
Here the php code:
$ar1=array(10,10,10,10,10,10,10,10,10,10);
$ar2 = array(0,0,0,0,0,0,0,0,0,0);
$c = 0;
foreach( $ar1 as $key => $value ){
$ar2[$c]=$value+$ar2[$c];
if ($ar2[$c]>25){$c++;}
}
I've got an array with about 40 keys. I'd like to have a small function that returns a summary array.
Right now I've got the following that works:
foreach ($all_data as $value){
$new_array[ $value['location'] ][ $value['manufacturer'] ][ $value['model'] ] += 1;
}
This returns an array with everything I need. However, the location, manufacturer and model could be changed up for a bunch of other values.
what I am trying to do is have something simple as:
$new_array = summarize($all_data,array('location','manufacturer','model','count'),array('list','list','list','count') );}
where this summarize function would build the call. I think I just need a bit of help on how to get it to run the string as code for this array. Otherwise I get
$current_selection = "[ $row_item['location'] ][ $row_item['manufacturer'] ][ $row_item['model'] ]"
$return_array{$current_selection} += 1;
Where the end goal is to have a function like:
function summarize($data_array, $fields_array, $process_array){
//data_array = associative multi-dimensional data array
//fields = values to pull from the data_array
//process = array specifying whether to list, sum, count, average, max, min
$return_array = array();
$current_selection = "";
foreach($fields_array as $field){
$current_selection .= '[ $row_item[\'' . $field . '\'] ]';
}
foreach ($data_array as $row_item){
//dynamic = DOES NOT WORK
$return_array[$current_selection] += 1;//eval? create function? abstract?
//another attempt
${'return_array' . $current_selection} += 1;
//Manual = Does work
//$return_array[ $row_item['location'] ][ $row_item['manufacturer'] ][ $row_item['model'] ] += 1;
}
}
Thanks for any help on how to do an indirect reference.
JC
RESOLUTION
The final version that managed to resolve this looks like the following, thanks to user: check, for getting me on the correct path.
function summarize($data_array, $fields_array, $process_array){
$return_array = array();
$i = 0;
foreach ($data_array as $row){
$ii = 0;
$temp = array();
$temp2 = array();
foreach($fields_array as $key=>$field){
if($process_array[$ii] == 'list') $temp[$ii] = $row[$field];
if($process_array[$ii] == 'count') $temp2[$ii] = 1;
if($process_array[$ii] == 'sum') $temp2[$ii] = $row[$field];
$ii++;
}
$unique = true;
$ii = 0;
foreach($return_array as $row2){
if(array_intersect_key($row2,$temp) == $temp){//$row2 == $temp){
$unique = false;
break;
}
$ii++;
}
if($unique){
$return_array[$i] = $temp;
if(!empty($temp2)) $return_array[$i] = array_merge($temp,$temp2);
$i++;
}else{
if(!empty($temp2)){
foreach($temp2 as $key => $value){
if($process_array[$key] == 'sum') $temp2[$key] = $return_array[$ii][$key] + $value;
if($process_array[$key] == 'count') $temp2[$key] = $return_array[$ii][$key] + 1;
if($process_array[$key] == 'max') $temp2[$key] = ($return_array[$ii][$key] < $value) ? $value : $return_array[$ii][$key];
if($process_array[$key] == 'min') $temp2[$key] = ($return_array[$ii][$key] > $value) ? $value : $return_array[$ii][$key];
//TODO:(JC) 'average' - need to create a count field if not present (or always despite and assume overhead of extra computations).
// - then just calculate the 'sum' and divide by the counter as a last step before returning the array.
}
$return_array[$ii] = array_merge($temp,$temp2);
}
}
}
print_r($return_array);
return $return_array;
}
Which gives the following result:
/*
CALL: summarize($data,array('location','manufacturer','model','model','volume','colourvolume'),array('list','list','list','count','sum','sum') );
[0] = location
[1] = manufacturer
[2] = model
[3] = model count
[4] = mono volume sum
[5] = colour volume sum
*/
Array
(
[0] => Array
(
[0] =>
[1] => HP
[2] => LaserJet 4000
[3] => 3
[4] => 3000
[5] => 0
)
...
[17] => Array
(
[0] => Room 114
[1] => CANON
[2] => iR3235
[3] => 1
[4] => 4012
[5] => 0
)
[18] => Array
(
[0] => Room 115
[1] => LEXMARK
[2] => T652
[3] => 1
[4] => 20
[5] => 0
)
)
alternatively, if I assume that's $field_array contains sequentially key fields from root to sub key, you can loop your $field_array within $data_array loop
function summarize($data_array, $fields_array, $process_array){
$return_array = array();
foreach ($data_array as $row){
$temp = array();
foreach($fields_array as $key=>$field){
$temp = $key==0?$row[$field]:$temp[$field];
}
if(!empty($temp)) $return_array[] = $temp;
}
return $return_array;
}
and this is my array, will summarize with these function
$array = array(
array("multi"=>array("dimensional"=>array("array"=>"foo1"))),
array("multi"=>array("dimensional"=>array("array"=>"foo2"))),
array("multi"=>array("dimensional"=>array("array"=>"foo3"))),
array("multi"=>array("dimensional"=>array("array"=>"foo4"))),
array("multi"=>array("dimensional"=>array("array"=>"foo5"))),
array("multi"=>array("dimensional"=>array("array"=>"foo6"))),
array("multi"=>array("dimensional"=>array("array"=>"foo7"))),
array("multi"=>array("dimensional"=>array("array"=>"foo8"))),
array("multi"=>array("dimensional"=>array("array"=>"foo9")))
);
print_r(summarize($array,array("multi","dimensional","array"),NULL));
Ouput
Array ( [0] => foo1 [1] => foo2 [2] => foo3 [3] => foo4 [4] => foo5 [5] => foo6 [6] => foo7 [7] => foo8 [8] => foo9 )
I have two arrays like so (however there can be more or less than 2 (any amount)):
[0] => Array
(
[assessedUsers] => Array
(
[0] => Array
(
[scores] => Array
(
[0] => 10
[1] => 10
[2] => 10
[3] => 10
)
)
[1] => Array
(
[scores] => Array
(
[0] => 9
[1] => 10
[2] => 0
[3] => 9
)
)
)
)
Where the length of the scores array is always the same in both arrays.
I would like to take each element from each array, one by one, and average them, then append them into a new array.
For example, the output of my desired function would look like this:
[1] => Array
(
[scores] => Array
(
[0] => 9.5
[1] => 10
[2] => 5
[3] => 9.5
)
)
Is there a function that can do this, or do I need a couple nested for() loops? If I need to use forl loops how would I go about doing it? I'm a little confused on the logic behind it.
Currently what I have is:
for ($i = 0; $i < sizeof($data["assessedUsers"]); $i++) {
for ($j = 0; $j < sizeof($data["assessedUsers"][$i]["scores"]); $j++) {
}
}
and I'm a little confused as to what to where to go next. Thanks in advance!
$mean = array_map( function($a, $b) { return ($a + $b) / 2; },
$data['assessedUsers'][0]['scores'],
$data['assessedUsers'][1]['scores']
);
var_dump($mean);
And append $mean anywhere you want. Or do you have more than 2 arrays? You did not state it in your question.
ps: for any number of subarrays
$arr = array(
array('scores' => array(10,10,10,10)),
array('scores' => array(9,10,0,9)),
array('scores' => array(1,2,3,4))
);
// remove arrays from the key
$tmp = call_user_func_array( function() { return func_get_args(); },
array_map( function($a) { return $a['scores']; }, $arr)
);
// add arrays by each element
$mean = array_map( function($val, $ind) use($tmp) {
$sum = 0;
foreach($tmp as $i => $t)
$sum += $t[$ind];
return $sum / ($i + 1);
}, $tmp[0], array_keys($tmp[0]));
var_dump($mean);
Probably two loops:
$newarray();
foreach($main_array as $user) {
foreach($user['assessedUser'][0]['scores'] as $score_key => $user0_value) {
$user1_value = $user['assessedUser'][1]['scores'][$score_key];
$average = ($user1_value + $user0_value) / 2;
... stuff into new array
}
}
I have solution for you, hope this help :)
$scores = array();
for ($i = 0; $i < sizeof($data["assessedUsers"]); $i++) {
for ($j = 0; $j < sizeof($data["assessedUsers"][$i]["scores"]); $j++) {
if(isset($scores[$j])){
$scores[$j] = ($scores[$j] + $data["assessedUsers"][$i]["scores"][$j]) / ($i +1);
}else{
$scores[] = $data["assessedUsers"][$i]["scores"][$j];
}
}
}
$scores[] = $scores;
view Example :)
http://codepad.org/upPjMEym
It should quite simple algorithm, but I just can't get around it.
I have some arrays in alphabetical order
[0] => Array
(
[0] => a
[1] => b
[2] => c
)
and for example
[0] => Array
(
[0] => a
[1] => b
[2] => c
[3] => d
)
and I need to sort them into rows. For example:
I should receive a table with 3 columns and as many rows as it may get and it should be in alphabetical order.
Here is an example:
First array should be converted into
[0] => Array
(
[0] => Array
(
[0] => a
[1] => b
[2] => c
)
)
But second one should be as
[1] => Array
(
[0] => Array
(
[0] => a
[1] => c
[2] => d
)
[1] => Array
(
[0] => b
)
)
I'm writing it in php, so if anyone can help I would be really appreciated.
UPD:
Code example:
function sortAsOrdered( array $categories )
{
foreach ( $categories as $groupId => $group )
{
$regroupMenuItems = array();
$limit = count( $group );
$rows = ceil( $limit / 3 );
for ( $i = 0; $i < $rows; ++$i )
{
$jumper = 0;
for ( $j = 0; $j < 3; $j++ )
{
if ( 0 == $jumper )
{
$jumper = $i;
}
if ( isset( $group[ $jumper ] ) )
{
$regroupMenuItems[ $i ][ $j ] = $group[ $jumper ];
}
$jumper = $jumper + $rows;
}
}
$categories[ $groupId ] = $regroupMenuItems;
}
return $categories;
}
Guys I solved this one. Here you could see my algorithm http://pastebin.com/xe2yjhYW.
But don't be sad your help will not go in vain. I probably will place bounty just for those who helped with this dificult algorithm for me.
Guys thanks one more time. Your thoughts inspired me to think differently.
array_chunk() wold have been the solution but as you want it to be specially sorted, that wouldn't help you much.
So here is my five cents:
function array_chunk_vertical($input, $size_max) {
$chunks = array();
$chunk_count = ceil(count($input) / $size_max);
$chunk_index = 0;
foreach ($input as $key => $value) {
$chunks[$chunk_index][$key] = $value;
if (++$chunk_index == $chunk_count) {
$chunk_index = 0;
}
}
return $chunks;
}
$array = array('a', 'b', 'c', 'd', 'e', 'f');
var_dump(array_chunk_vertical($array, 2));
Which will give you:
array
0 =>
array
0 => string 'a' (length=1)
3 => string 'd' (length=1)
1 =>
array
1 => string 'b' (length=1)
4 => string 'e' (length=1)
2 =>
array
2 => string 'c' (length=1)
5 => string 'f' (length=1)
The downside of this function is that you can only tell the max number of elements in a chunk, and then it equally divides the array to chunks. So for [4] and max_size 3 you will get [2,2] unlike the expected [3,1].
<?php
$five_el = array('a', 'b', 'c', 'd', 'e');
$two_el = array('a', 'b');
$three_el = array('a', 'b', 'c');
$six_el = array('a', 'b', 'c', 'd', 'e', 'f');
function multid($sorted_array) {
$mulidarray = array();
$row = 0;
$column = 0;
foreach ($sorted_array as $value) {
if ($column == 3) {
$row++;
}
$column++;
if (!isset($mulidarray[$row])) {
$mulidarray[$row] = array();
}
$multidarray[$row][] = $value;
}
return $multidarray;
}
var_dump(multid($five_el));
var_dump(multid($two_el));
var_dump(multid($three_el));
var_dump(multid($six_el));
array_chunk is a natural first approach to the problem, but it won't do exactly what you need to. If the solution is provided that way, you need to either restructure the resulting array or restructure the input before processing it, as below:
$input = range('a', 'k'); // arbitrary
$columns = 3; // configure this
$rows = ceil(count($input) / $columns);
// fugly, but this way it works without declaring a function
// and also in PHP < 5.3 (on 5.3 you'd use a lambda instead)
$order = create_function('$i',
'$row = (int)($i / '.$rows.');'.
'$col = $i % '.$rows.';'.
'return $col * ('.$columns.' + 1) + $row;');
// $order is designed to get the index of an item in the original array,
// and produce the index that item would have if the items appeared in
// column-major order instead of row-major as they appear now
$array = array_map($order, array_keys($input));
// replace the old keys with the new ones
$array = array_combine($array, $input);
// sort based on the new keys; this will effectively transpose the matrix,
// if it were already structured as a matrix instead of a single-dimensional array
ksort($array);
// done!
$array = array_chunk($array, $columns);
print_r($array);
See it in action.
Let's see if this is nearer the mark
function splitVerticalArrayIntoColumns($aInput, $iNumberOfColumns) {
//output array
$aOutput = array();
//the total length of the input array
$iInputLength = count($aInput);
//the number of rows will be ceil($iInputLength / $iNumberOfColumns)
$iNumRows = ceil($iInputLength / $iNumberOfColumns);
for($iInputIndex = 0; $iInputIndex < $iInputLength; $iInputIndex++) {
$iCurrentRow = $iInputIndex % $iNumRows;
$aOutput[$iCurrentRow][] = $aInput[$iInputIndex];
}
//return
return $aOutput;
}
Which - when run thus:
$aList = array("a", "e", "d", "b", "c");
echo 'array("a", "e", "d", "b", "c")' . "\n\n";
print_r(splitVerticalArrayIntoColumns($aList, 3));
Gives:
array("a", "e", "d", "b", "c")
Array
(
[0] => Array
(
[0] => a
[1] => d
[2] => c
)
[1] => Array
(
[0] => e
[1] => b
)
)
That's not sorting each row yet but is that the kind of thing you're after?
begin facepalm edit
... or of course, array_chunk($aList, 3) after you've sorted it O_o
http://uk3.php.net/manual/en/function.array-chunk.php
I'll leave everything below for reference or whatever - I'd completely forgotten about array_chunk()
end facepalm edit
I'd use a modulo in a loop where you're counting the array index (after sorting the array) - for instance if you're trying to split an array into 3 "columns" you could try something like:
if($iIndex % 3 == 0) {
//... create a new array
}
else {
//... add to an existing array
}
EDIT code example:
$aList = array("a", "e", "d", "b", "c");
sort($aList);
$iDesiredNumberOfColumns = 3;
$iListLength = count($aList);
$aListInColumns = array();
$iRowNumber = 0;
for($iIndex = 0; $iIndex < $iListLength; $iIndex++) {
$iColumnNumber = $iIndex % 3;
if($iIndex != 0 && $iColumnNumber == 0) {
$iRowNumber++;
}
$aListInColumns[$iRowNumber][$iColumnNumber] = $aList[$iIndex];
}
Just ran it on my local server (and corrected the typo), and it outputs as:
Array
(
[0] => Array
(
[0] => a
[1] => b
[2] => c
)
[1] => Array
(
[0] => d
[1] => e
)
)
There's probably a tidier way of doing it (that's a little procedural) but it should do the job.
How about:
$arrs = array(
array('a','b','c'),
array('a','b','c','d'),
array('a','b','c','d','e'),
array('a','b','c','d','e','f'),
array('a','b','c','d','e','f','g')
);
$nbcols = 3;
foreach ($arrs as $arr) {
$arr_size = count($arr);
$nblines = ceil($arr_size/$nbcols);
$res = array();
$l = 0;
foreach ($arr as $el) {
if ($l == $arr_size - 1 && count($res[0]) < $nbcols) $l=0;
$res[$l%$nblines][] = $el;
$l++;
}
print_r($res);
}
output:
Array
(
[0] => Array
(
[0] => a
[1] => b
[2] => c
)
)
Array
(
[0] => Array
(
[0] => a
[1] => c
[2] => d
)
[1] => Array
(
[0] => b
)
)
Array
(
[0] => Array
(
[0] => a
[1] => c
[2] => e
)
[1] => Array
(
[0] => b
[1] => d
)
)
Array
(
[0] => Array
(
[0] => a
[1] => c
[2] => e
)
[1] => Array
(
[0] => b
[1] => d
[2] => f
)
)
Array
(
[0] => Array
(
[0] => a
[1] => d
[2] => g
)
[1] => Array
(
[0] => b
[1] => e
)
[2] => Array
(
[0] => c
[1] => f
)
)
In order to do this, you need to do two operations:
First, split the array into 3 groups, as evenly as possible.
function array_grouped($arr, $group_count)
{
if (!count($arr)) return array();
$result = array();
for ($i = $group_count; $i > 0; --$i)
{
# break off the next ceil(remaining count / remaining columns) elements
# (avoiding FP math, cause that way lies madness)
$result[] = array_splice($arr, 0, ((count($arr)-1) / $i) + 1);
}
return $result;
}
Then, "transpose" the array, so that rows and columns switch places.
function array_transposed($arr)
{
$result = array();
foreach ($arr as $x => $subarr)
{
foreach ($subarr as $y => $val)
{
if (!isset($result[$y])) $result[$y] = array();
$result[$y][$x] = $val;
}
}
return $result;
}
array_transposed(array_grouped($arr, 3)) gives you entries in the order you want them.
YAYAYAY!! I've got it. You could turn this into a function if you'll be doing it regularly.
# Here we setup our array and the number of columns we want.
$myArray = range('a','d');
$numCols = 3;
# Here we break ourselves up into columns
for ($i = 0; $i < $numCols; $i++) {
$numRows = ceil(count($myArray) / ($numCols - $i));
$columns[$i] = array_slice($myArray,0,$numRows);
$myArray = array_slice($myArray,$numRows);
}
# Here we transpose our array to be in rows instead of columns.
for ($i = 0; $i < $numCols; $i++) {
for ($j = 0; $j < count($columns[$i]); $j++) {
$rows[$j][$i] = $columns[$i][$j];
}
}
# Our rows are now in $rows
var_dump($rows);
The output from this is:
array(2) {
[0]=>
array(3) {
[0]=>
string(1) "a"
[1]=>
string(1) "c"
[2]=>
string(1) "d"
}
[1]=>
array(1) {
[0]=>
string(1) "b"
}
}
If to say it shortly, then here is a method for that algorithm.
/**
* #param array $toTransform
* #param int $columnsMax
* #return array
*/
private function transformation( array $toTransform, $columnsMax = 3 )
{
// First divide array as you need
$listlen = count( $toTransform );
$partlen = floor( $listlen / $columnsMax );
$partrem = $listlen % $columnsMax;
$partition = array();
$mark = 0;
for ( $px = 0; $px < $columnsMax; $px++ )
{
$incr = ( $px < $partrem ) ? $partlen + 1 : $partlen;
$partition[ $px ] = array_slice( $toTransform, $mark, $incr );
$mark += $incr;
}
// Secondly fill empty slots for easy template use
$result = array();
for ( $i = 0; $i < count( $partition[0] ); $i++ )
{
$tmp = array();
foreach ( $partition as $column )
{
if ( isset( $column[ $i ] ) )
{
$tmp[] = $column[ $i ];
}
else
{
$tmp[] = '';
}
}
$result[] = $tmp;
}
return $result;
}
Also I included PHPUnit test for that. You can find it at, that link.