How do I combine these two arrays, so that the keys stay the same, but the values are arithmetically determined?
Note - the keys might not always line up in each array, per my example:
$Array1 = [4 => 100, 5 => 200, 6 => 100, 7 => 400];
$Array2 = [2 => 300, 5 => -100, 16 => -500];
Desired output:
$Array3 = [2 => 300, 4 => 100, 5 => 100, 6 => 100, 7 => 400, 16 => -500];
You can use array_map for this:
$Array3 = array_map(function($a,$b) {return $a+$b;},$Array1,$Array2);
However this will only work if you have the same keys in both arrays (which, in your example, you don't).
If this is an issue, the easiest workaround would probably be:
$allKeys = array_merge(array_keys($Array1),array_keys($Array2));
$Array3 = Array();
foreach($allKeys as $k) {
$Array3[$k] = (isset($Array1[$k]) ? $Array1[$k] : 0)
+(isset($Array2[$k]) ? $Array2[$k] : 0);
}
EDIT Just realised the above code is not optimal. Rewriting:
$allKeys = array_unique(array_merge(array_keys($Array1),array_keys($Array2)));
// rest of code as above
Actually not sure if the overhead of repeated keys is more or less than the overhead of checking uniqueness...
You can foreach over each array and add them to a result array.
//$array3 = array();
//foreach($array1 as $k=>$v){
// $array3[$k] = $v;
//}
$array3 = $array1;
foreach($array2 as $k=>$v){
$array3[$k] = isset($array3[$k]) ? $array3[$k]+$v : $v;
}
Related
Below is an array of strings and numbers. How could the string and number values be split into separate arrays (with strings in one array and numbers in another array)?
array('a','b','c',1,2,3,4,5,'t','x','w')
You could also do this in one line using array_filter()
$numbers = array_filter($arr,function($e){return is_numeric($e);});
$alphas = array_filter($arr,function($e){return !is_numeric($e);});
print_r($numbers);
print_r($alphas);
Loop through them, check if is_numeric and add to appropriate array:
$original = array('a','b','c',1,2,3,4,5,'t','x','w');
$letters = array();
$numbers = array();
foreach($original as $element){
if(is_numeric($element)){
$numbers[] = $element;
}else{
$letters[] = $element;
}
}
https://3v4l.org/CAvVp
Using a foreach() like in #jnko's answer will be most performant because it only iterates over the array one time.
However, if you are not concerned with micro-optimization and prefer to write concise or functional-style code, then I recommend using array_filter() with is_numeric() calls, then making key comparisons between the first result and the original array.
Code: (Demo)
$array = ['a','b',0,'c',1,2,'ee',3,4,5,'t','x','w'];
$numbers = array_filter($array, 'is_numeric');
var_export($numbers);
var_export(array_diff_key($array, $numbers));
Output:
array (
2 => 0,
4 => 1,
5 => 2,
7 => 3,
8 => 4,
9 => 5,
)
array (
0 => 'a',
1 => 'b',
3 => 'c',
6 => 'ee',
10 => 't',
11 => 'x',
12 => 'w',
)
$data = array('a','b','c',1,2,3,4,5,'t','x','w');
$integerArray = array();
$stringArray = array();
$undefinedArray = array();
foreach($data as $temp)
{
if(gettype($temp) == "integer")
{
array_push($integerArray,$temp);
}elseif(gettype($temp) == "string"){
array_push($stringArray,$temp);
}else{
array_push($undefinedArray,$temp);
}
}
I have a array like this:
$row_arr_1=array(7,9,5,10);
now I want to get the result array like this:
$row_arr_2=array(3,2,4,1);
Explanation:
As 10 is the largest value in row_arr_1, then it will be replaced with value 1.
Similarly, as 9 is the 2nd highest value of row_arr_1, then it will be replaced by 2 and so on.
I tried to sort the values of row_arr_1 but the position is changed.
How
can i get my desired result?
It can be done using rsort() and array_search()
$row_arr_1=array(7,9,5,10);
$row_copy = $row_arr_1;
$row_arr_2 = array();
rsort($row_copy);
foreach($row_arr_1 as $val) {
$row_arr_2[] = array_search($val, $row_copy) + 1;
}
print_r($row_arr_2);
https://eval.in/990078
You can use arsort() to sort the array while preserving keys, and use those keys for your array via array_keys():
$row_arr_1 = array(7,9,5,10);
$row_arr_1_backup = $row_arr_1;
arsort($row_arr_1_backup);
$row_arr_2 = array_keys($row_arr_1_backup);
asort($row_arr_2);
$row_arr_2 = array_keys($row_arr_2);
array_walk($row_arr_2, function(&$item, &$key) {
$item = $item + 1;
});
You have to duplicate the original array, since arsort will sort the actual array it points to, rather than returning a new array.
$row_arr_1_old = array(7, 9, 5, 10);
$row_arr_1 = array(7, 9, 5, 10);
rsort($row_arr_1);
$test = [];
foreach ($row_arr_1_old as $key => $value) {
$test[] = array_search($value, $row_arr_1);
}
print_r($test);
For best efficiency try to reduce total function calls; this especially means minimizing / eliminating iterated function calls.
This is my slightly more efficient version of ahsan's answer.
Code: (Demo)
$copy = $arr = [7, 9, 5, 10];
rsort($arr); // generates: [10, 9, 7, 5]
$flipped = array_flip($arr); // generates: [10 => 0, 9 => 1, 7 => 2, 5 => 3]
foreach($copy as $v) {
$result[] = ++$flipped[$v]; // adds one to each accessed value from $flipped
}
var_export($result);
Output:
array (
0 => 3,
1 => 2,
2 => 4,
3 => 1,
)
Im not sure if ive wrote the question properly but ill elaborate more on what i need.
I have two objects which i need to change to array and they have keys 1,2,3 but they have different values i need to subtract the values from the array where the keys are the same, I hope this makes sense.
Things ive tried to far
Push them both to 1 array and do the math from there (can't figure out how to do this)
use array_diff to find the difference in the arrays but didn't work.
All help appreciated any more information needed will be provided
Example Arrays:
Array 1
1 => 300.00,
2 => 300.00,
3 => 300.00
Array 2
1 => 200.00,
2 => 200.00,
3 => 200.00
Desired output
1 => 100.00,
2 => 100.00,
3 => 100.00
The best option for this seems to be a for loop
$arr1 = [300, 300, 300];
$arr2 = [200, 200, 200];
$arr_length = sizeof($arr1) -1;
$minus_arr = [];
for($i = 0; $i <= $arr_length; $i++){
$minus = $arr1[$i] - $arr2[$i];
array_push($minus_arr, $minus);
}
print_r($minus_arr);
I took for granted your given arrays above, it sounds like the arrays you're using are either not the same size or have strings or nulls in them so check for an int first.
<?php
$arr1 = [300, 300, 300];
$arr2 = [200, 200, 200];
$arr_length = sizeof($arr1) -1;
$minus_arr = [];
for($i = 0; $i <= $arr_length; $i++){
if(is_int($arr1[$i]) && is_int($arr2[$i])){
$minus = $arr1[$i] - $arr2[$i];
array_push($minus_arr, $minus);
}
}
print_r($minus_arr);
I hope I do not misunderstand your question.
My method is iterate through 2 arrays, and whenever their keys are the same, do the operation. Here is a example:
function diff($arr1, $arr2) {
$result = [];
foreach($arr1 as $key1 => $value1) {
foreach($arr2 as $key2 => $value2) {
if ($key1 == $key2) {
$result[$key1] = $value1 - $value2;
}
}
}
return $result;
}
I see there is Laravel in your tag, if you're using laravel, I'm sure that you can achieve this better with Collection. The document is here. It provides you a more 'OO' way (similar to javascript) you can operate arrays in php.
For an indexed array,
function diff($arr1, $arr2){
$arr3=array();
for($i=0;$i<count($arr1);$i++){
$arr3[$i]=$arr1[$i]-$arr2[$i];
}
print_r($arr3);
}
$arr1=array(300,300,300);
$arr2=array(100,100,100);
diff($arr1, $arr2);
//Displays 200, 200, 200, as expected
Given an associative array like this, how can you shuffle the order of keys that have the same value?
array(a => 1,
b => 2, // make b or c ordered first, randomly
c => 2,
d => 4,
e => 5, // make e or f ordered first, randomly
f => 5);
The approach I tried was to turn it into a structure like this and shuffle the values (which are arrays of the original keys) and then flatten it back into the original form. Is there a simpler or cleaner approach? (I'm not worried about efficiency, this is for small data sets.)
array(1 => [a],
2 => [b, c], // shuffle these
4 => [d],
5 => [e, f]); // shuffle these
function array_sort_randomize_equal_values($array) {
$collect_by_value = array();
foreach ($array as $key => $value) {
if (! array_key_exists($value, $collect_by_value)) {
$collect_by_value[$value] = array();
}
// note the &, we want to modify the array, not get a copy
$subarray = &$collect_by_value[$value];
array_push($subarray, $key);
}
arsort($collect_by_value);
$reordered = array();
foreach ($collect_by_value as $value => $array_of_keys) {
// after randomizing keys with the same value, create a new array
shuffle($array_of_keys);
foreach ($array_of_keys as $key) {
array_push($reordered, $value);
}
}
return $reordered;
}
I rewrote the entire code, since I found another way which is a lot simpler and faster than the old one(If you are still interested in the old one see the revision):
old code (100,000 executions): Ø 4.4 sec.
new code (100,000 executions): Ø 1.3 sec.
Explanation
First we get all unique values from the array with array_flip(), since then the values are the keys and you can't have duplicate keys in an array we have our unique values. We also create an array $result for then storing our result in it and $keyPool for storing all keys for each value.
Now we loop through our unique values and get all keys which have the same value into an array with array_keys() and save it in $keyPool with the value as key. We can also right away shuffle() the keys array, so that they are already random:
foreach($uniqueValues as $value => $notNeeded){
$keyPool[$value] = array_keys($arr, $value, TRUE);
shuffle($keyPool[$value]);
}
Now we can already loop through our original array and get a key with array_shift() from the $keyPool for each value and save it in $result:
foreach($arr as $value)
$result[array_shift($keyPool[$value])] = $value;
Since we already shuffled the array the keys already have a random order and we just use array_shift(), so that we can't use the key twice.
Code
<?php
$arr = ["a" => 1, "b" => 1, "c" => 1, "d" => 1, "e" => 1, "f" => 2,
"g" => 1, "h" => 3, "i" => 4, "j" => 5, "k" => 5];
function randomize_duplicate_array_value_keys(array $arr){
$uniqueValues = array_flip($arr);
$result = [];
$keyPool = [];
foreach($uniqueValues as $value => $notNeeded){
$keyPool[$value] = array_keys($arr, $value, TRUE);
shuffle($keyPool[$value]);
}
foreach($arr as $value)
$result[array_shift($keyPool[$value])] = $value;
return $result;
}
$result = randomize_duplicate_array_value_keys($arr);
print_r($result);
?>
(possible) output:
Array (
[b] => 1
[g] => 1
[a] => 1
[e] => 1
[d] => 1
[f] => 2
[c] => 1
[h] => 3
[i] => 4
[k] => 5
[j] => 5
)
Footnotes
I used array_flip() instead of array_unique() to get the unique values from the array, since it's slightly faster.
I also removed the if statement to check if the array has more than one elements and needs to be shuffled, since with and without the if statement the code runs pretty much with the same execution time. I just removed it to make it easier to understand and the code more readable:
if(count($keyPool[$value]) > 1)
shuffle($keyPool[$value]);
You can also make some optimization changes if you want:
Preemptively return, if you get an empty array, e.g.
function randomize_duplicate_array_value_keys(array $arr){
if(empty($arr))
return [];
$uniqueValues = array_flip($arr);
$result = [];
//***
}
Preemptively return the array, if it doesn't have duplicate values:
function randomize_duplicate_array_value_keys(array $arr){
if(empty($arr))
return [];
elseif(empty(array_filter(array_count_values($arr), function($v){return $v > 1;})))
return [];
$uniqueValues = array_flip($arr);
$result = [];
//***
}
Here's another way that iterates through the sorted array while keeping track of the previous value. If the previous value is different than the current one, then the previous value is added to a new array while the current value becomes the previous value. If the current value is the same as the previous value, then depending on the outcome of rand(0,1) either the previous value is added to the new list as before, or the current value is added to the new list first:
<?php
$l = ['a' => 1,'b' => 2, 'c' => 2,
'd' => 4,'e' => 5,'f' => 5];
asort($l);
$prevK = key($l);
$prevV = array_shift($l); //initialize prev to 1st element
$shuffled = [];
foreach($l as $k => $v) {
if($v != $prevV || rand(0,1)) {
$shuffled[$prevK] = $prevV;
$prevK = $k;
$prevV = $v;
}
else {
$shuffled[$k] = $v;
}
}
$shuffled[$prevK] = $prevV;
print_r($shuffled);
For example i have an array like this $array = ('a' => 2, 'b' => 1, 'c' => 4); and i need to swap a with c to get this $array = ('c' => 4, 'b' => 1, 'a' => 2);. Wht is the best way for doing this without creating new array? I know that it is possible with XOR, but i also need to save indexes.
array_splice would be perfect, but unfortunately it doesn't preserve the keys in the inserted arrays. So you'll have to resort to a little more manual slicing and dicing:
function swapOffsets(array $array, $offset1, $offset2) {
list($offset1, $offset2) = array(min($offset1, $offset2), max($offset1, $offset2));
return array_merge(
array_slice($array, 0, $offset1, true),
array_slice($array, $offset2, 1, true),
array_slice($array, $offset1 + 1, $offset2 - $offset1 - 1, true),
array_slice($array, $offset1, 1, true),
array_slice($array, $offset2 + 1, null, true)
);
}
If you want to purely swap the first and the last positions, here's one way to do it:
$first = array(key($array) => current($array)); // Get the first key/value pair
array_shift($array); // Remove it from your array
end($array);
$last = array(key($array) => current($array)); // Get the last key/value pair
array_pop($array); // Remove it from the array
$array = array_merge($last, $array, $first); // Put it back together
Gives you:
Array
(
[c] => 4
[b] => 1
[a] => 2
)
Working example: http://3v4l.org/r87qD
Update: And just for fun, you can squeeze that down quite a bit:
$first = array(key($array) => current($array));
$last = array_flip(array(end($array) => key($array)));
$array = array_merge($last, array_slice($array,1,count($array) - 2), $first);
Working example: http://3v4l.org/v6R7T
Update 2:
Oh heck yeah, we can totally do this in one line of code now:
$array = array_merge(array_flip(array(end($array) => key($array))), array_slice($array,1,count($array) - 2), array_flip(array(reset($array) => key($array))));
Working example: http://3v4l.org/QJB5T
That was fun, thanks for the challenge. =)