CODEWITHSUNDEEP
php
Gracie williams
Gracie williams

Reputation: 1145

Get numbers around the key in array

Suppose I have an array like below

   [0] => 25
    [1] => 30
    [2] => 35
    [3] => 40
    [4] => 45
    [5] => 50
    [6] => 55
    [7] => 60
    [8] => 65
    [9] => 70

If i input my key as 4 , I need to get nearest 2 arrays , example

[2] => 35
[3] => 40
[4] => 45
[5] => 50
[6] => 55

right now I use something like below.

$key = 4;
$count = 2;
$slice = array_slice($array,$key-$count,4+($count-1));

But if my $key is 1 and count is 2, I need something like

    [0] => 25
    [1] => 30
    [2] => 35
    [3] => 40

and if key is 8 I need 

  [6] => 55
    [7] => 60
    [8] => 65
    [9] => 70

I cannot achieve this slice code above , so some one guide some other way , thank you.

Upvotes: 1

Views: 59

Answers (4)

ascsoftw
ascsoftw

Reputation: 3476

Below Code satisfy your test cases

$array = array(
    '0' => 25,
    '1' => 30,
    '2' => 35,
    '3' => 40,
    '4' => 45,
    '5' => 50,
    '6' => 55,
    '7' => 60,
    '8' => 65,
    '9' => 70,
);

$key = 8;
$count = 2;

$slice = array_slice(
    $array, 
    ( ( $key - $count ) > 0 ) ? ( $key - $count) : 0  , 
    ( ( $key - $count ) > 0 ) ? ( (2 * $count) + 1 ) :  ( (2 * $count) + ( $key - $count + 1 )  )
);

Here is the online demo

Upvotes: 1

Don't Panic
Don't Panic

Reputation: 41810

Setting the offset to $key - $count is correct. You can use max() to keep it from going negative.

$offset = max(0, $key - $count);

For the length, the basic calculation is 2 * $count + 1. By adding min($key - $count, 0) to that, you can subtract any of the left-side count that would extend below zero.

$length = 2 * $count + 1 + min($key - $count, 0);

You don't need to worry if the slice extends beyond the count of the array, that part will be ignored.

$slice = array_slice($array, $offset, $length);

Upvotes: 1

Stan Brown
Stan Brown

Reputation: 11

Erwin's answer is correct.

If you also want to ensure the same number of values are selected if a key at the end of the array is given you will need to check for this:

$key = 4;
$count = 2;
if ( ($key - $count) < 0){
  $key = $count;
} elseif ( ($key + $count) > count($array) ) {
  $key = count($array) - $count;
}
$slice = array_slice($array,$key-$count,$key+($count-1));

Upvotes: 0

Erwin Moller
Erwin Moller

Reputation: 2408

You probably mean:

$slice = array_slice($array,$key-$count,**$key**+($count-1));

Just make sure you don't go negative:

$key = 4;
$count = 2;
if ( ($key - $count) < 0){
  $key = $count;
}
$slice = array_slice($array,$key-$count,$key+($count-1));

Upvotes: 0

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