array_slice for associative array

Question

I have an array with indexes as timestamps. I tried array_slice to get all values between a time range but it doesn't seem to work.

$data = array_slice(["1549440811" => 1, "1549448226" => 2, "1551108588" => 3 ], 0, 1549460338);

I should get the $data as ["1549440811" => 1, "1549448226" => 2] but it doesn't work that way.

To get the right data I have to use

$data = array_slice(["1549440811" => 1, "1549448226" => 2, "1551108588" => 3 ], 0, 2);

But the problem is the records can have random timestamps and no. of records. So I am unable to figure out the offset which is 2 in this case.

I know the code below with a few changes might work for small range but not for my timestamps as $myrange would have a lot of data.

$myrange = range(0,1549460338);
$output = array_intersect(["1549440811" => 1, "1549448226" => 2, "1551108588" => 3 ] , $myrange );

I am avoiding looping through the array as the array has a lot of data. Also I have a lot of timestamps to check. This code is a simplified logic of a bigger code with records from database indexed with timestamps.

Is there any other way I could get the desired data?

why you filtering array, why not filter in mysql query or whatever use you database?? — Nageen
– Nageen, Commented Apr 3, 2019 at 8:36
@nageennayak i have a loop on data I get from database and the timestamp 1549460338 is of a record in the loop, I avoided querying the database in the loop to fetch the other data. I got the other data in one query indexed by timestamp instead — Mehravish Temkar
– Mehravish Temkar, Commented Apr 3, 2019 at 8:39
@nageennayak the other data that I am fetching is being reused by other records in the loop as well — Mehravish Temkar
– Mehravish Temkar, Commented Apr 3, 2019 at 8:41

dWinder · Accepted Answer · 2019-04-03 09:36:21Z

2

Simple for-loop should do:

$arr = ["1549440811" => 1, "1549448226" => 2, "1551108588" => 3 ];
$range = "1549460338";
foreach($arr as $k => $v) {
    if ($range > $k)
        break;
    $newArr[$k] = $v;
}

You can also use array_filter (doc):

$filtered = array_filter( $arr,
    function ($key) use ($range) {return $range > $key;},
    ARRAY_FILTER_USE_KEY
);

Example: 3v4l

Edit:

Fastest way (consider your array is sorted) is to extract the keys with $keys = array_keys($arr); and then search for the $range using binary search (O(log(n))) -> then use array_slice with that index.

edited Apr 3, 2019 at 9:36

answered Apr 3, 2019 at 8:29

dWinder

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7 Comments

Mehravish Temkar Over a year ago

I prefer not to loop as the data is too much.

dWinder Over a year ago

@MehravishTemkar update the post using array_filter - is it better?

Mehravish Temkar Over a year ago

thanks. let me implement it in my code and get back to you

Danyal Sandeelo Over a year ago

@MehravishTemkar on the backend, it would be loop

Mehravish Temkar Over a year ago

thanks. thousands of records in the array as well as for timestamps, avoiding things that would slow it down. @DanyalSandeelo

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