PHP get closest time to given array of times [duplicate] - php

Question

This question already has answers here:
How to get closest date compared to an array of dates in PHP
(6 answers)
Closed 3 years ago.
I have an array called $timeslots with timeslots like:
array:32 [▼
0 => "2018-12-15T12:00:00.0000000"
1 => "2018-12-15T12:15:00.0000000"
2 => "2018-12-15T12:30:00.0000000"
3 => "2018-12-15T12:45:00.0000000"
4 => "2018-12-15T13:00:00.0000000"
5 => "2018-12-15T13:15:00.0000000"
6 => "2018-12-15T13:45:00.0000000"
7 => "2018-12-15T14:15:00.0000000"
8 => "2018-12-15T14:30:00.0000000"
9 => "2018-12-15T14:45:00.0000000"
10 => "2018-12-15T15:00:00.0000000"
11 => "2018-12-15T15:15:00.0000000"
12 => "2018-12-15T15:30:00.0000000"
13 => "2018-12-15T15:45:00.0000000"
14 => "2018-12-15T16:15:00.0000000"
15 => "2018-12-15T16:45:00.0000000"
16 => "2018-12-15T17:00:00.0000000"
17 => "2018-12-15T17:30:00.0000000"
18 => "2018-12-15T17:45:00.0000000"
19 => "2018-12-15T18:30:00.0000000"
20 => "2018-12-15T18:45:00.0000000"
21 => "2018-12-15T19:15:00.0000000"
22 => "2018-12-15T19:45:00.0000000"
23 => "2018-12-15T20:15:00.0000000"
24 => "2018-12-15T20:45:00.0000000"
25 => "2018-12-15T21:00:00.0000000"
26 => "2018-12-15T21:15:00.0000000"
27 => "2018-12-15T21:30:00.0000000"
28 => "2018-12-15T21:45:00.0000000"
29 => "2018-12-15T22:00:00.0000000"
30 => "2018-12-15T22:15:00.0000000"
31 => "2018-12-15T22:30:00.0000000"
]
Also, I have a variable like:
$expected_time = 2018-12-15T18:00:00.0000000; // this can be different value, so its not unique value
$expected_time is never into array $timeslots but I need to find closest value to $expected_time... How I can do that?
How I can get the closest timeslot value from array $timeslots to $expected_time and calculate the difference in minutes?
Any idea?

Answer 1

As Nico mentioned in the comments, it's pretty straightforward. Just looping and calculating the time difference.
$timeslots = [...];
$expected_time = "2018-12-15T18:00:00.0000000";
$timestamp = strtotime($expected_time);
$diff = null;
$index = null;
foreach ($timeslots as $key => $time) {
$currDiff = abs($timestamp - strtotime($time));
if (is_null($diff) || $currDiff < $diff) {
$index = $key;
$diff = $currDiff;
}
}
echo $timeslots[$index];

Answer 2

Here is one solution fitting your requirements:
function findClosestDate($expectedDate,$dates)
{
$differenceInMinutes = null;
$expectedDate = new DateTime($expectedDate);
$expectedDateEpoch = $expectedDate->getTimestamp();
$returnIndex = -1;
for($i = 0; $i<count($dates); $i++)
{
$dateObject = new DateTime($dates[$i]);
$dateEpoch = $dateObject->getTimestamp();
$difference = abs($expectedDateEpoch-$dateEpoch);
$difference = $difference/60;
if($differenceInMinutes === null || $difference < $differenceInMinutes)
{
$differenceInMinutes = $difference;
$returnIndex = $i;
}
}
return array(
"closest" => $dates[$returnIndex],
"difference" => $differenceInMinutes
) ;
}
This makes use of the DateTime class to create a DateTime object and get the respective timestamp. The minutes are then calculated by the absolute difference between the expectedDate and the entry in the dates array. After iterating over the whole array, the closest match and the difference is returned in one array.

Answer 3

as your list is already sorted - u can put the element into array and use sort again - and it will be much faster then calculating the diff in each iteration.
<?php
$timeslots = [
...
];
$expected_time = "2018-12-15T18:00:00.0000000";
$counter = count($timeslots);
$timeslots = array_flip($timeslots);
$timeslots[$expected_time] = $counter;
ksort($timeslots);
while (key($timeslots) !== $expected_time) {
$prev = key($timeslots);
next($timeslots);
}
next($timeslots);
$next = key($timeslots);
$expected_time = new \DateTime($expected_time);
$closestDiff = min(($expected_time)->diff(new \DateTime($prev)), (new \DateTime($next))->diff($expected_time));
var_dump($closestDiff->i);