How can I keep only every second element from array usign PHP?

Question

Below is a part of my produced array. How can I keep only every second element usign PHP?

I have tried this until now without luck, maybe it depends on the structure of the array, I didn't understand.

$size = count($array);
$result = array();
for ($i = 0; $i < $size; $i += 2) {
  $result[] = $array[$i];
}
var_dump($result);

this is my array below:

   Array
    (
        [0] => Array
            (
                [0] => 
                                        11.490
                [1] => 
                                        11.490
                [2] => 
                                        13.490
                [3] => 
                                        13.490
                [4] => 
                                        17.490
                [5] => 
                                        17.490
                [6] => 
                                        20.990
                [7] => 
                                        20.990
                [8] => 
                                        14.290
                [9] => 
                                        14.290
                [10] => 
                                        14.490
                [11] => 
                                        14.490
                [12] => 
                                        19.990
                [13] => 
                                        19.990

@JayBlanchard The code I used is preg_match_all and I don't believe you need it since I provide the result of an array — EnexoOnoma, Jan 24 '17 at 14:04
Every other or unique? http://php.net/manual/en/function.array-unique.php — chris85, Jan 24 '17 at 14:04
Now here's an [XY problem](http://xyproblem.info) if you ever saw one. — JJJ, Jan 24 '17 at 14:06
@JayBlanchard I have added what I tried so far, you can remove your downvote if you like — EnexoOnoma, Jan 24 '17 at 14:09
You could probably get `preg_match_all` to return it the way you want. — AbraCadaver, Jan 24 '17 at 14:09
Probably the best solution would be to FIX the way you create this array rather than trying to frig the array after the initial mistake — RiggsFolly, Jan 24 '17 at 14:11
your code isn't terribly wrong per se; but obviously the array you are trying to filter has another array inside it. try: `$result[] = $array[0][$i]` — yivi, Jan 24 '17 at 14:11
Possible duplicate of [How to access N-th element of an array in PHP](http://stackoverflow.com/questions/24825281/how-to-access-n-th-element-of-an-array-in-php) — Masivuye Cokile, Jan 24 '17 at 14:17
How do you know it's not working as you would expect? By any chance were you expecting the result to contain ` [0] => 11.490` and then `[2] => 11.490` instead of `[0]` and then `[1]`? — giusti, Jan 24 '17 at 14:32

Emaro · Accepted Answer · 2017-01-24T14:49:40.507

0

Use array_filter (php.net)

function odd($var)
{
    return($var & 1);
}

$array[0] = array_filter($array[0], "odd", ARRAY_FILTER_USE_KEY);

EDIT:
Of course you can also use an "even" method

EDIT 2:
Change to match the code from the op.
From $array to $array[0]

EDIT 3:
Add a missing semicolon

edited Jan 24 '17 at 14:49

answered Jan 24 '17 at 14:14

Emaro

1,397
1
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21

2

while this is not wrong, wont work with his input. it's a nested array. – yivi Jan 24 '17 at 14:15
Then you pass $array[0] as a parameter – Emaro Jan 24 '17 at 14:16
2

put it in your answer? – yivi Jan 24 '17 at 14:17
Hi. You need at least php 5.6 to use the flag *ARRAY_FILTER_USE_KEY*. If it doesn't work it also don't know the answer. But check out the php.net link for more informations on array_filter(). – Emaro Jan 24 '17 at 14:45

Antony · Answer 2 · 2017-01-24T14:20:42.127

-5

How about using unset on every other element?

<?php
$array = array('1','1','2','2','4','4','5','5');

for($i = count($array) - 1; $i > 0; $i -= 2){
    unset($array[$i]);
}

edited Jan 24 '17 at 14:20

answered Jan 24 '17 at 14:08

Antony

1,253
11
19

1

`array_unique` removes all duplicate, while he wants to remove only every other element. Using `array_unique` could therefore remove too many values. – Antony Jan 24 '17 at 14:11
2

But if you look at your code, it will only process HALF the array, and then reduce that by a half. So your result will be one quarter of the array – RiggsFolly Jan 24 '17 at 14:12
Right, fixed. Note that the new solution will only work if the array has an even number of elements. Otherwise, `$i` should start at `count($array)-2`. – Antony Jan 24 '17 at 14:18
2

`$i > 0 / 2` ? That's interesting. – yivi Jan 24 '17 at 14:19
1

Did you test it. I DID! And that does not work either. The array is unchanged – RiggsFolly Jan 24 '17 at 14:20
I also did :) http://sandbox.onlinephpfunctions.com/code/32bde617876abbcce738ffea6d287549d51ac673 – Antony Jan 24 '17 at 14:21

How can I keep only every second element from array usign PHP?

2 Answers2