Sum current month value with previous last 5 month value in array - php

Question

I have an array with some values. Here I need to make a calculation for Year 2019 only.
$array = array(
"date_2019_12" => 0,
"date_2019_11" => 0,
"date_2019_10" => 0,
"date_2019_09" => 0,
"date_2019_08" => 0,
"date_2019_07" => 0,
"date_2019_06" => 0,
"date_2019_05" => 0,
"date_2019_04" => 0,
"date_2019_03" => 0,
"date_2019_02" => 0,
"date_2019_01" => 10,
"date_2018_12" => 1,
"date_2018_11" => 2,
"date_2018_10" => 3,
"date_2018_09" => 4,
"date_2018_08" => 5,
"date_2018_07" => 6,
);
krsort($array);
From this array, I need to calculate the sum of previous five months & current month starting "date_2019_01".
That means I need final array result like below:
"date_2019_01" => 25(10+1+2+3+4+5)
"date_2019_02" => 20(0+10+1+2+3+4)
"date_2019_03" => 16(0+0+10+1+2+3)
"date_2019_04" => 13(0+0+0+10+1+2)
... until "date_2019-12".
I have spend many times finding solution but I could not. Can anybody help me?
I have tried following code and somewhere now I am lost.
$newArr = array();
foreach($array as $key => $val) {
$explode = explode("_", $key);
$value = (int)$explode[2];
for($i = 0; $i <= 5; $i++) {
$newArr[$array[$explode[0].'_'.$explode[1].'_'.$value]] = $array[$explode[0].'_'.$explode[1].'_'.$value];
$value--;
}
}

Answer 1

You don't need to nest the loops, you can use one loop, array_slice and array_sum.
krsort($array);
$year = "2019";
$keys = array_keys($array); //save keys since we use array_values in the loop
foreach(array_values($array) as $k => $v){
// If the year is found in the key slice out the next six item and sum them
if(strpos($keys[$k], $year) !== false) $res[$keys[$k]] = array_sum(array_slice($array, $k, 6));
}
var_dump($res);
https://3v4l.org/LSQRg

Answer 2

This code will do what you want. It uses a nested loop to iterate over each month and the 5 preceding months, creating a sum for each one from the different date values in the array:
$year = 2019;
$sums = array();
for ($i = 1; $i <= 12; $i++) {
$sum = 0;
for ($j = $i - 5; $j <= $i; $j++) {
$y = $year;
$m = $j;
if ($m <= 0) {
$m += 12;
$y -= 1;
}
$date = sprintf("date_%4d_%02d", $y, $m);
$sum += $array[$date];
}
$date = sprintf("date_%4d_%02d", $year, $i);
$sums[$date] = $sum;
}
print_r($sums);
Output:
Array (
[date_2019_01] => 25
[date_2019_02] => 20
[date_2019_03] => 16
[date_2019_04] => 13
[date_2019_05] => 11
[date_2019_06] => 10
[date_2019_07] => 0
[date_2019_08] => 0
[date_2019_09] => 0
[date_2019_10] => 0
[date_2019_11] => 0
[date_2019_12] => 0
)
Demo on 3v4l.org

Answer 3

Use: https://3v4l.org/7AYfT
$newArr = array();
foreach($array as $key => $val) {
$i=1;
$newArr[$key] = $val;
foreach($array as $key2 => $val2){
if($key>$key2 && $i <= 5){
$newArr[$key] += $val2;
$i++;
}
}
}
array(18) {
["date_2019_12"]=>
int(0)
["date_2019_11"]=>
int(0)
["date_2019_10"]=>
int(0)
["date_2019_09"]=>
int(0)
["date_2019_08"]=>
int(0)
["date_2019_07"]=>
int(0)
["date_2019_06"]=>
int(10)
["date_2019_05"]=>
int(11)
["date_2019_04"]=>
int(13)
["date_2019_03"]=>
int(16)
["date_2019_02"]=>
int(20)
["date_2019_01"]=>
int(25)
["date_2018_12"]=>
int(21)
["date_2018_11"]=>
int(20)
["date_2018_10"]=>
int(18)
["date_2018_09"]=>
int(15)
["date_2018_08"]=>
int(11)
["date_2018_07"]=>
int(6)
}

Answer 4

There are two steps I have performed.
Step 1: Sorting custom format array by keys
// sort the array first by date of given format
uksort($array, function ($a, $b) {
$t1 = strtotime(str_replace(["date_", "_"], ["", "-"], $a) . '-01');
$t2 = strtotime(str_replace(["date_", "_"], ["", "-"], $b) . '-01');
return $t1 - $t2;
});
Step 2: Main logic to given condition with inline documentation
$flag = false;
$result = [];
foreach ($array as $key => $value) {
if ($key != 'date_2019_01' && !$flag) {
continue; // check until 'date_2019_01' wont come
} else {
$flag = true; // set the flag and skip above condition
$curKey = array_search($key, array_keys($array), true); // get integer index of date_2019_01
if ($key !== false) { // if key exists
$slice = array_slice($array, $curKey - 5, 6, true); // from current index last 5(6-5, 7-5,8-5,....) to 6(including current element)
$result[$key] = array_sum($slice); // sum of there values
}
}
}
Brief of things I have used to make it clear for understanding of applications of it.
uksort — Sort an array by keys using a user-defined comparison function
array_keys — Return all the keys or a subset of the keys of an array
array_search — Searches the array for a given value and returns the first corresponding key if successful
array_slice — Extract a slice of the array
array_sum — Calculate the sum of values in an array
str_replace — Replace all occurrences of the search string with the replacement string