I have two arrays of associative arrays with different keys. I need to merge them into a single array of associative arrays, with nulls or empty strings for keys that do not exist at higher indices. For example:
$first = array(array('x'=>'1','y'=>'2'));
$second = array(array('z'=>'3'),array('z'=>'4'));
The result should look like this:
$result = array(
array(
'x'=>'1',
'y'=>'2',
'z'=>'3'
),
array(
'x'=>'',
'y'=>'',
'z'=>'4'
)
);
The function that merges these arrays needs to be able to handle two or more arrays. Here's what I came up with:
// allArrays can be many arrays of all sizes and will be different each time this process runs
$allArrays = array($first, $second);
$longestArray = max($allArrays);
$data = array();
for($i = 0; $i < count($longestArray); ++$i) {
$dataRow = array();
foreach ($allArrays as $currentArray) {
if (isset($currentArray[$i])) {
foreach ($currentArray[$i] as $key => $value) {
$dataRow[$key] = $value;
}
} else {
foreach ($currentArray[0] as $key => $value) {
$dataRow[$key] = '';
}
}
}
$data[] = $dataRow;
}
It works, but I think the nested for loops cause poor performance on large arrays, and it's pretty illegible. Is there a better way to tackle this problem?
Unfortunately, it looks like this is the best way to solve this problem. I'll answer the question with the example from above in case it helps anyone in the future.
// allArrays can be many arrays of all sizes and will be different each time this process runs
$allArrays = array($first, $second);
$longestArray = max($allArrays);
$data = array();
for($i = 0; $i < count($longestArray); ++$i) {
$dataRow = array();
foreach ($allArrays as $currentArray) {
if (isset($currentArray[$i])) {
foreach ($currentArray[$i] as $key => $value) {
$dataRow[$key] = $value;
}
} else {
foreach ($currentArray[0] as $key => $value) {
$dataRow[$key] = '';
}
}
}
$data[] = $dataRow;
}
How can I implement the code:
$numberList3 = array();
for($i = 0; $i < 10; $i++)
{
$numberList3[$i] = $i;
}
print_r($numberList3);
Using a foreach loop as the no. of times the loop is going to execute is decided by the user at run time.
Any suggestion.?
Use array_fill maybe?
<?php
$n = 10;
$arr = array_fill(0,$n,0);
foreach($arr as $k => $v) {
$arr[$k] = $k;
}
print_r($arr);
Or, as suggested by #deceze, use range
<?php
$n = 10;
$arr = array();
foreach(range(0,$n-1) as $v) {
$arr[$v] = $v;
}
print_r($arr);
Or when the value is the same as the key, you can use just this:
<?php
$n = 10;
$arr = range(0,$n-1);
// no foreach needed
print_r($arr);
foreach() works for object and array not for a single value.
What you can do create an array or object from users input.
like:
$userInput = 10;
$forEachArray = array_fill(0, $userInput, 0);
$arrayToDisplay = array();
foreach($forEachArray as $key){
$arrayToDisplay[$key] = $key;
}
print_r($arrayToDisplay);
let me start off by saying what I have works just fine. However, I was wondering if there was a method using foreach loops, instead of while loops, that will return the same result. My current code is:
$a[0] = $_GET['a1'];
$a[1] = $_GET['a2'];
$a[2] = $_GET['a3'];
$a[3] = $_GET['a4'];
$a[4] = $_GET['a5'];
$a[5] = $_GET['a6'];
$a[6] = $_GET['a7'];
$a[7] = $_GET['a8'];
$a[8] = $_GET['a9'];
$a[9] = $_GET['a10'];
$a[10] = $_GET['a11'];
$a[11] = $_GET['a12'];
$a[12] = $_GET['a13'];
$a[13] = $_GET['a14'];
$a[14] = $_GET['a15'];
$a[15] = $_GET['a16'];
$a[16] = $_GET['a17'];
$a[17] = $_GET['a18'];
$a[18] = $_GET['a19'];
$a[19] = $_GET['a20'];
$a[20] = $_GET['a21'];
$a[21] = $_GET['a22'];
$a[22] = $_GET['a23'];
$a[23] = $_GET['a24'];
$a[24] = $_GET['a25'];
$a[25] = $_GET['a26'];
$a[26] = $_GET['a27'];
$a[27] = $_GET['a28'];
$array1 = array(
array(-0.0165333833412173,-0.805148897111146,-0.253228140499216,-0.184436610496828,-0.182460815146422,-0.562680616467753),
array(0.0530980021095432,0.197367160352892,0.486754591654999,0.100148472516492,0.129649075750223,-0.0891313538023273),
array(1.20820560236013,1.60297691019929,1.88645801788488,1.4097784563,1.35491780171462,1.83839262576814),
array(0.35474704442591,0.669288291278341,-0.618871707987998,0.314393917137463,0.369309934864932,0.302877707428276),
array(1.73737846681824,1.23045039205127,1.74985170545799,2.53444768504332,0.947425891979588,2.49693773110446),
array(1.08515864048978,1.19974869194067,1.40391203998614,0.645993089768699,1.18500365352365,0.183710871687018),
array(-0.158201130751605,0.245894811416122,-0.13491139550657,0.268781009345758,0.584094496717681,-0.475038989317082),
array(2.69120997158388,2.6335032877555,2.1678974119528,1.98159587601917,2.47871441914596,3.11218576826585),
array(1.58301428618536,1.4690581543491,1.64181831092486,1.31270093574087,0.956030437566211,1.68095459548238),
array(0.567053945109392,0.672686283651576,0.50520628014895,0.573859412747649,0.906581004455213,0.675935843127413),
array(2.21154924140175,2.4629227185282,2.44302564998387,1.76594656224375,2.24292394905905,2.46555856986067),
array(0.789058773638184,0.56494483459565,1.02220848055446,0.740827710977414,0.0568788365193514,0.974084436394248),
array(-1.22527151151768,-0.37116067796664,-0.993915606653743,-0.265414040283105,-0.0483919594705323,-1.26478189171631),
array(1.93198111668015,0.978691339072353,0.896606685235391,1.43344220993764,1.44428119515243,0.832846974841109),
array(0.0960968892129648,0.179429676667834,0.653561055735465,0.611111687937286,0.420917607921928,0.788124847059183),
array(-0.570188484564322,-0.367869613869776,-0.425708923999659,0.58428081962228,0.431696028180505,-0.560777966949268),
array(2.18753554884398,2.10453220450978,2.18396016604212,1.53663043726462,1.6128493800773,2.47023229651768),
array(0.933680338305853,0.701683572817621,1.05817969240128,1.13326689801564,1.06305023491714,1.28172788495342),
array(0.237030103809889,1.19429662809383,1.32352397170755,0.787441428409051,1.06861486730769,0.196323518345157),
array(1.27102015175144,0.999617071482296,1.14337292692749,1.79352497701309,1.14261585172827,1.18874166503307),
array(0.746730730970985,0.584005303699165,0.00845233248507581,0.617844244971367,0.646839413026708,0.393004935019083),
array(1.33877796293032,1.18403793988876,1.16686497194317,1.18487924665819,0.796233877768925,1.21668080067963),
array(1.66146357909026,1.52622605987311,1.51673796371559,2.45659237209795,1.58826974938031,1.87667392945756),
array(1.23205756178945,1.25461474916892,1.0738857243227,1.21949513612512,0.847503017550969,1.33075294766838),
array(0.976236852070675,1.0676137689421,1.08390543200419,1.19114160706157,0.804407032221587,0.918305581716723),
array(1.0514345299356,1.24825633668808,1.15750685444102,1.34538988886631,1.24490007119083,0.994386901437322),
array(-50.5445732202499,-53.6034355984409,-52.2301074110166,-59.4416059910645,-50.3559798265968,-51.5135149950383),
);
$array2 = array();
$x = 0;
while($x < COUNT($array1)){
$y = 0;
while($y < COUNT($array1[$x])){
$array2[$x][$y] = $array1[$x][$y] * $a[$x];
//echo($array2[$x][$y] . ', ');
$y++;
}
//echo('<br>');
$x++;
}
Again, while this works, I am trying to get into the habit of writing cleaner code. Additionally, I am still relatively new to PHP, so I'm still struggling a bit with some of its syntax and structuring.
Thanks in advance.
This should work identical to what you have.
$array2 = array();
foreach($a as $k1=>$a1)
{
foreach($array1[$k1] as $k2=>$a2)
{
$array2[$k1][$k2] = $a2 * $a1;
}
}
The basic format of a foreach loop is foreach($array as $key=>$value) if you don't need the array key, you can shorten it to foreach($array as $value).
You can reduce the code by directly accessing the $_GET values instead of copying them into $a.
$result = array();
foreach($array1 as $k1 => $array2) {
foreach($array2 as $k2 => $value) {
$result[$k1][$k2] = $value * $_GET['a'.($k1+1)];
}
}
I have two arrays in my code.
Need to perform a foreach loop on both of these arrays at one time. Is it possible to supply two arguments at the same time such as foreach($array1 as $data1 and $array2 as $data2)
or something else?
If they both the same keys, you can do this:
foreach($array1 as $key=>data1){
$data2 = $array2[$key];
}
Assuming both have the same number of elements
If they both are 0-indexed arrays:
foreach ($array_1 as $key => $data_1) {
$data_2 = $array_2[$key];
}
Otherwise:
$keys = array_combine(array_keys($array_1), array_keys($array_2));
foreach ($keys as $key_1 => $key_2) {
$data_1 = $array_1[$key_1];
$data_2 = $array_2[$key_2];
}
Dont use a foreach. use a For, and use the incremented index, eg. $i++ to access both arrays at once.
Are both arrays the same size always?
Then this will work:
$max =sizeof($array);
for($i = 0; $i < $max; $i++)
array[$i].attribute
array2[$i].attribute
If the arrays are different sizes, you may have to tweak your approach. Possibly use a while.
iterative methods:
http://php.net/manual/en/control-structures.while.php
http://php.net/manual/en/control-structures.for.php
http://php.net/manual/en/control-structures.do.while.php
use for or while loop e.g.
$i = 0;
while($i < count($ar1) && $i < count($ar2) ) // $i less than both length !
{
$ar1Item = $ar1[$i];
$ar2Item = $ar2[$i];
$i++;
}
No to my knowledge with foreach, but can be easily done with for:
<?php
$cond1 = 0<count($array1);
$cond2 = 0<count($array2);
for ($i=0;$cond1 || $cond2;$i++)
{
if ($cond1)
{
// work with $array1
}
if ($cond2)
{
// work with $array2
}
$cond1 = 0<count($array1);
$cond2 = 0<count($array2);
}
?>
Hi anybody can help me to find the maximum value of the array that are given in the below . i expect the result of 650 is the maximum value....
$my_array = array(array(128,300,140)10,15,array(130,array(500,650)));
Here you go, using RecursiveArrayIterator in 3 readable lines of code:
$it = new RecursiveIteratorIterator(new RecursiveArrayIterator($array));
$flattenedArray = iterator_to_array($it);
$max = max($flattenedArray);
Or, if you want to not flatten (and copy), but prefer to iterate (uses far less memory, but slower):
$it = new RecursiveIteratorIterator(new RecursiveArrayIterator($array));
$max = 0;
foreach ($it as $value) {
$max = max($value, $max);
}
Flatten the array, then call max() on it. The return value of max() should be 650 from your example.
Also possible is
$data = array(array(128,300,140),10,15,array(130,array(500,650)));
$max = 0;
array_walk_recursive(
$data,
function($val) use (&$max) {
if($val > $max) $max = $val;
}
);
echo $max; // 650
You could also do it recursively, if the item is an array, call the function again to return the max item from that array.
In the end you should have always the max item and then in the last iteration, you could call the max from those results.
This does the trick:
function flatten($ar) {
$toflat = array($ar);
$res = array();
while (($r = array_shift($toflat)) !== NULL) {
foreach ($r as $v) {
if (is_array($v)) {
$toflat[] = $v;
} else {
$res[] = $v;
}
}
}
return $res;
}
$arr = array(array(128,300,140),10,15,array(130,array(500,650)));
echo max(array_flatten($arr));
EDIT: Updated flatten array with the one at How to "flatten" a multi-dimensional array to simple one in PHP?
<?php
$my_array = array(array(128,300,140),10,15,array(130,array(500,650)));
function findLargest($arr) {
$largest = 0;
foreach ($arr as $item) {
if (is_array($item)) {
$item = findLargest($item);
}
if ($item > $largest) {
$largest = $item;
}
}
return $largest;
}
echo "Largest is ".findLargest($my_array)."\n";
?>
function maximum($in)
{
if (!is_array($in)) $max = $in;
else foreach ($in as $element)
{
$elementMax = maximum($element);
if (isset($max)) $max = max($elementMax, $max); else $max = $elementMax;
}
return $max;
}