merge array of different length php

Question

Let's say that I have two arrays like this:

$arr1 = array(
array('position' => 1),
array('position' => 2),
array('position' => 3),
array('position' => 4),
array('position' => 5),
array('position' => 6),
array('position' => 7)
);

$arr2 = array(      
array(
    'a' => 'A1', 
    'b' => 'B1',
    'c' => 'C1'
),
array(
    'a' => 'A2',
    'b' => 'B2',
    'c' => 'C2'
),
array(
    'a' => 'A3',
    'b' => 'B3',
    'c' => 'C3'
)
);

The goal is to have a resulting array where the key position from the first array is copied to each array in the second array like this:

$final_arr = array(
array(
    'a' => 'A1',
    'b' => 'B1',
    'c' => 'C1', 
    'position' => 1
),
array(
    'a' => 'A2',
    'b' => 'B2',
    'c' => 'C2', 
    'position' => 2
),
array(
    'a' => 'A3',
    'b' => 'B3',
    'c' => 'C3', 
    'position' => 3
)
);

Why can't I just do this with array_merge? Any idea?

NOTE As you can see above, the arrays don't have the same length

Thank you for any help

foreach() loop through array2

user557846
– user557846

2014-03-10 01:11:05 +00:00
Commented Mar 10, 2014 at 1:11 — user557846
– user557846, Commented Mar 10, 2014 at 1:11
As @Dagon suggests, iteration is the most obvious method.

Popnoodles
– Popnoodles

2014-03-10 01:11:59 +00:00
Commented Mar 10, 2014 at 1:11 — Popnoodles
– Popnoodles, Commented Mar 10, 2014 at 1:11
What do you want to happen to $arr1 > 3?

Mike
– Mike

2014-03-10 01:16:04 +00:00
Commented Mar 10, 2014 at 1:16 — Mike
– Mike, Commented Mar 10, 2014 at 1:16

user557846 · Accepted Answer · 2014-03-10 01:16:18Z

2

$new=array();
foreach ($arr2 as $k=>$v){

$new[]=$v+$arr1[$k];
}

print_r($new);

http://codepad.viper-7.com/tYkEWa

answered Mar 10, 2014 at 1:16

user557846

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3 Comments

user765368 Over a year ago

Can I do this with while loop?

Stfvns Over a year ago

excuse me , has been bothering you all. I have the same problem like this. I want ask when my arr2 loger then arr1 how to give a value 0 to the arr2 position = 0 ?

user557846 Over a year ago

@Stfvns if you have a question, post a new question.

kojiro · Accepted Answer · 2014-03-10 01:25:17Z

0

array_merge would just join the arrays. You'd get an array made up of the values (subarrays) of $arr1 and $arr2. (array_merge actually has two different behaviors, depending on whether the arrays it operates on have numeric keys or string/associative keys.) What you want is:

foreach($arr1 as $idx => $subar) {
  if (!isset($arr2[$idx])) {
    break;
  }
  $arr2[$idx]['position'] = $subar['position'];
}

I'm assuming the 'position' key is fixed. If it's not, then you have to guarantee that each $subar has a single and known key to extract using something like array_shift(array_keys($subar)).

edited Mar 10, 2014 at 1:25

answered Mar 10, 2014 at 1:12

kojiro

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4 Comments

user557846 Over a year ago

your finial output does not match user765368's as you loop arr1 not arr2 (codepad.viper-7.com/TrsvAq)

kojiro Over a year ago

@Dagon I copy the subarray from array 1 to the 'position' key in array 2. Since OP asked for array_merge, I felt updating an existing array would be more aligned with that request.

user557846 Over a year ago

yes, but his finial array has 3 elements, not the 7 you return .. all good, up to the OP ;-)

Mike Over a year ago

The question seems a bit ambiguous to me. The OP is asking for a "merge" and then shows an array only containing 3 elements.

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