PHP get ranges of same values from array - php

Question

Is there any way to get the key range of same values and make a new array?
Let's say we have an Array Like this in php :
$first_array = ['1'=>'a','2'=>'a','3'=>'a','4'=>'b','5'=>'b','6'=>'a','7'=>'a'];
How can i get this array? Is there any function for this?
$second_array = ['1-3'=>'a','4-5'=>'b','6-7'=>'a'];

Answer 1

Loop through it, extract the keys, generate the ranges and insert to the new array -
$first_array = ['1'=>'a','2'=>'a','3'=>'a','4'=>'b','5'=>'b'];
$flip = array();
foreach($first_array as $key => $val) {
$flip[$val][] = $key;
}
$second_array = [];
foreach($flip as $key => $value) {
$newKey = array_shift($value).' - '.end($value);
$second_array[$newKey] = $key;
}
Output
array(2) {
["1 - 3"]=>
string(1) "a"
["4 - 5"]=>
string(1) "b"
}

Answer 2

regarding your first question you can get range of each value using foreach() loop.
$first_array = ['1'=>'a','2'=>'a','3'=>'a','4'=>'b','5'=>'b'];
foreach($first_array as $key=>$value)
{
//do your coding here, $key is the index of the array and $value is the value at that range, you can use that index and value to perform array manipulations
}
Regarding your second question it not exactly clear what are trying to implement there. But what ever you want to do like creating a new array with modified index and other things can be done within this foreach() loop itself
I hope this helps you.

Answer 3

If someone is still looking for an answer, here is what I did.
Given the array
$first_array = ['0'=>'a',
'1'=>'a',
'2'=>'a',
'3'=>'a',
'4'=>'a',
'5'=>'b',
'6'=>'b',
'7'=>'a',
'8'=>'a']
I build a multidimensional array, in which each element is an array of three more elements:
[0] - The value in the first array
[1] - The key where the value starts repeating
[2] - The last key where the value stops repeating
The code
$arrayRange = [];
for($i = 0; $i < count($first_array); $i++){
if(count($arrayRange) == 0){
// The multidimensional array is still empty
$arrayRange[0] = array($first_array[$i], $i, $i);
}else{
if($first_array[$i] == $arrayRange[count($arrayRange)-1][0]){
// It's still the same value, I update the value of the last key
$arrayRange[count($arrayRange)-1][2] = $i;
}else{
// It's a new value, I insert a new array
$arrayRange[count($arrayRange)] = array($first_array[$i], $i, $i);
}
}
}
This way you get a multidimensional array like this:
$arrayRange[0] = array['a', 0, 4];
$arrayRange[1] = array['b', 5, 6];
$arrayRange[2] = array['a', 7, 8];