Replacing the unusual number in php array - php

Question

I have the array of numbers in php like following
[2021-06-04] => Array
(
[09:15:04] => 1.51
[09:15:27] => 1.32
[09:15:46] => 14.29
[09:16:05] => 14.03
[09:18:05] => 13.97
[09:18:24] => 13.88
[09:18:42] => 13.94
[09:19:01] => 13.80
[09:19:05] => 13.86
[09:19:23] => 13.97
[09:19:41] => 6.99
[09:20:00] => 14.14
[09:20:06] => 14.08
[09:20:25] => 14.04
)
In above array items .. 1.51,1.32 and 6.99 is somewhat off , so i want to replace then with next element so it result array should look like below.
[2021-06-04] => Array
(
[09:15:04] => 14.29
[09:15:27] => 14.29
[09:15:46] => 14.29
[09:16:05] => 14.03
[09:18:05] => 13.97
[09:18:24] => 13.88
[09:18:42] => 13.94
[09:19:01] => 13.80
[09:19:05] => 13.86
[09:19:23] => 13.97
[09:19:41] => 14.14
[09:20:00] => 14.14
[09:20:06] => 14.08
[09:20:25] => 14.04
)
I can get array average using
$a = array_filter($a);
$average = array_sum($a)/count($a);
echo $average;
and I tried something like below
foreach($arr as $key=>$val)
{
if($avg-$val) > 5)
{
$arr[$key] = $nextactualelem; // How do I get next correct element whose $avg-$val is less than 5
}
}
P.s : hi , is it possible to get next 10 elements average.. instead of total average.. because in larger sets its not working fine.. because larger data sets ranging from 10 to 30... so difference of 5 is not working on the initial smaller values.or is there any other faster way to do it like difference between next and previous number..

Answer 1

If you're going to make changes to the array you're working on foreach is not your best choice. referring to keys is troublesome, variable values ale not clean on every run. Generally if you need to do something with the array you're iterating use a for loop instead.
Now since you're going to replace the values, we have a slight issue. Looking at edge cases. What if we want to go over the array in reverse (that makes sense since we want to replace an anomaly with the next value) but the last value is an anomaly? Still reverse order is a good choice but we need to make sure that at least the last value is a valid one.
Given the fact that the keys are rather arbitrary we can't use a for loop at this point. Thankfully we can use the internal array pointer to move around.
$arr = [
'09:15:04' => 1.51,
'09:15:27' => 1.32,
'09:15:46' => 14.29,
'09:16:05' => 14.03,
'09:18:05' => 13.97,
'09:18:24' => 13.88,
'09:18:42' => 13.94,
'09:19:01' => 13.80,
'09:19:05' => 13.86,
'09:19:23' => 13.97,
'09:19:41' => 6.99,
'09:20:00' => 14.14,
'09:20:06' => 14.08,
'09:20:25' => 14.04
];
$average = array_sum($arr)/count($arr);
end($arr); // We move the pointer to the end of the array;
//... do some verification magic here
// so we have a valid starting value on the end of the array
while(prev($arr) != false) { // move one step back while we have values
if (($average - current($arr)) > 5) {
$key = key($arr); // Grab the current key
$arr[$key] = next($arr); // replace the value with the next
prev($arr); // put the pointer back in the right place
}
}
var_dump($arr);
Note that if you run this the 6.99 will remain in the array as it's only 4.71 away from the average. So some tweaks to your conditions might be in order.
EDIT:
taking the new information We could try something along the lines of:
$lookup[] = end($arr); // We move the pointer to the end of the array and place it in a lookup array
//... do some varification magic here so we have a valid starting value on the end of the array
while(prev($arr) !== false) { // move one step back while we have values
$average = array_sum($lookup)/count($lookup); // calculate the current average based on lookup
if (abs($average - current($arr)) > 2) { // if the difference from the current average is more the 2 points
$arr[key($arr)] = next($arr); // replace the value with the next
prev($arr); // put the pointer back in the right place
}
$lookup[] = current($arr); // add the current value to the average
if (count($lookup) > 10) { // if we have more then 10 values in the lookup
array_shift($lookup); // Shift an element off the beginning of array
}
}
This should smooth things out ;)

Answer 2

loop through the reverse of your array, saving the last value, and replace the odd values for the last value that you saved before.
UPDATE:
Now $avg is the average of the next 10 available values.
$arr = [
'09:15:04' => 1.51,
'09:15:27' => 1.32,
'09:15:46' => 14.29,
'09:16:05' => 14.03,
'09:18:05' => 13.97,
'09:18:24' => 13.88,
'09:18:42' => 13.94,
'09:19:01' => 13.80,
'09:19:05' => 13.86,
'09:19:23' => 13.97,
'09:19:41' => 6.99,
'09:20:00' => 14.14,
'09:20:06' => 14.08,
'09:20:25' => 14.04,
];
$avg = 0;
$inverseArr = array_reverse($arr);
$lastValue = false;
$offset = -1;
foreach ($inverseArr as $key => $val) {
if (($avg - $val) > 5 && $lastValue !== false) {
$arr[$key] = $lastValue;
}
else {
$lastValue = $val;
}
$nextTen = array_slice($arr, $offset, 10);
$avg = array_sum($nextTen) / count($nextTen);
$offset--;
}
// array (size=14)
// '09:15:04' => float 14.29
// '09:15:27' => float 14.29
// '09:15:46' => float 14.29
// '09:16:05' => float 14.03
// '09:18:05' => float 13.97
// '09:18:24' => float 13.88
// '09:18:42' => float 13.94
// '09:19:01' => float 13.8
// '09:19:05' => float 13.86
// '09:19:23' => float 13.97
// '09:19:41' => float 14.14
// '09:20:00' => float 14.14
// '09:20:06' => float 14.08
// '09:20:25' => float 14.04