Split an array into two arrays based on identical values - php

Question

I have this array:
$arrayAll = [
'156' => '1',
'157' => '1',
'158' => '2',
'159' => '1',
'160' => '2',
'161' => '1'
];
where the keys are unique - they don't ever repeat. And the value could be either 1 or 2 - nothing else.
And I need to "split" this $arrayAll array into $array1 - that will contain everything with value 1 and $array2 - that will contain everything with value 2 so in the end I will have:
$array1 = [
'156' => '1',
'157' => '1',
'159' => '1',
'161' => '1'
];
and
$array2 = [
'158' => '2',
'160' => '2'
];
and as you can see, I will have the keys from the original array will remain the same.
What is the simplest thing to do to separate the original array like this?

Answer 1

This is probably the simplest way.
Loop it and create a temporary array to hold the values then extract the values to your array 1 and 2.
Foreach($arrayAll as $k => $v){
$res["array" . $v][$k] = $v;
}
Extract($res);
Var_dump($array1, $array2);
https://3v4l.org/6en6l
Updated to use extract and a method of variable variables.
The update means it will work even if there is a value "3" in the input array.
https://3v4l.org/jbvBf

Answer 2

Use foreach and compare each value and assign it to a new array.
$array1 = [];
$array2 = [];
foreach($arrayAll as $key=>$val){
if($val == 2){
$array2[$key] = $val;
}else{
$array1[$key] = $val;
}
}
print_r($array1);
print_r($array2);
Demo

Answer 3

The simplest thing to do is to use a foreach loop.
$array = [
'156' => '1',
'157' => '1',
'158' => '2',
'159' => '1',
'160' => '2',
'161' => '1'
];
$array1 = [];
$array2 = [];
foreach ($array as $key => $value)
// If value is 1, add to array1
// If value is not 1, add value to array2
if ($value === '1')
$array1[$key] = $value;
else
$array2[$key] = $value;
echo var_dump($array1);
echo '<br>';
echo var_dump($array2);

Answer 4

Use indirect reference:
$arrayAll = array("156"=>"1", "157"=>"1", "158"=>"2", "159"=>"1", "160"=>"2", "161"=>"1");
foreach($arrayAll as $key=>$value) {
$name = "array".$value;
$$name[$key] = $value;
}
echo "<pre>";
print_r($array1);
print_r($array2);
echo "</pre>";

Answer 5

//your array
$yourArray = [
'156' => '1',
'157' => '1',
'158' => '2',
'159' => '1',
'160' => '2',
'161' => '1'
];
With the conditions you mentioned just build two arrays, you can use array_keys with the second parameter that accepts a search value
$array1 = array_keys($yourArray, '1');
$array2 = array_keys($yourArray, '2');
If you don't want to use array_keys, go for an iteration
$array1 = array();
$array2 = array();
foreach($yourArray as $key=>$value){
//will always be 1 or 2, so an if-else is enought
if($value == 1){
$array1[] = $key;
} else {
$array2[] = $key;
}
}
And that's it.
Check this link for array_keys
If you have more than 2 values, the following will work and can be reused for other cases
You want to group them according to the values
$arrayOfValues = array_values($yourArray);
//this returns only the values of the array
$arrayOfUniqueValues = array_unique($arrayOfValues);
//this returns an array with the unique values, also with this u consider
//the posibility for more different values
//also u can get the unique values array on a single line
$arrayIfUniqueValues = array_unique(array_values($yourArray));
The array you will return
$theReturn = array();
foreach($arrayOfUniqueValues as $value ){
//what does this do?
//for each iteration it creates a key in your return array "$theReturn"
//and that one is always equal to the $value of one of the "Unique Values"
//array_keys return the keys of an array, and with the second parameter
//it acceps a search parameter, so the keys it return are the ones
//that matches the value, so here u are getting the array already made
$theReturn[$value] = array_keys($yourArray, $value);
}
The var_dump, in this case, will look like this
array(2) {
[1]=>
array(4) {
[0]=>
int(156)
[1]=>
int(157)
[2]=>
int(159)
[3]=>
int(161)
}
[2]=>
array(2) {
[0]=>
int(158)
[1]=>
int(160)
}
}
Hope my answer helps you, I tried to organize the solutions starting with the shortest/simplest.
Edit:
I forgot you needed the key value too, at least in this solution the array is always referring to the value, like $array1, $array2 or the $key references to the value as in the last solution

Answer 6

The simplest solution for separating an array into others based on the values involves:
Getting its unique values using array_unique.
Looping over these values using foreach.
Getting the key-value pairs intersecting with the current value using array_intersect.
Code:
# Iterate over every value and intersect it with the original array.
foreach(array_unique($arrayAll) as $v) ${"array$v"} = array_intersect($arrayAll, [$v]);
Advantage:
The advantage of this answer when compared to other given answers is the fact that it uses array_unique to find the unique values and therefore iterates only twice instead of n times.
Check out a live demo here.