How to concatenate arrays element recursively [duplicate] - php

Question

This question already has answers here:
Joining similar data from two indexed arrays
(2 answers)
Closed 5 months ago.
I'm working on a project and I'm stacked since 2 days, this is my problem: I have two arrays and want to retrieve the second item in each object in Array_2 and concatenate it to the content of each object in first Array_1 in PHP.
Array_1
[[1453274700000,24011],[1453275000000,24222],[1453275300000,24284],[1453275600000,24331],...]
Array_2
[[1453274700000,51951],[1453275000000,52093],[1453275300000,52251],[1453275600000,52288],...]
Wanted_array
[[1453274700000,24011,51951],[1453275000000,24222,52093],[1453275300000,24284,52251],[1453275600000,24331,52288]...]

Answer 1

A functional solution:
$result = array_map(function (array $a1, array $a2) {
return array_merge($a1, [$a2[1]]);
}, $array_1, $array_2);
This assumes that all items are in order and only need to be merged by their order, not by their first value.

Answer 2

If you want $item[0] to define what "group" each value belongs to, you can iterate through the first array and save $item[0] as the key and $item[1] as the value. Do the same for the second array. Now iterate through the saved array for array1, and check if the saved array for array2 contains the same keys. Do the same for array2 (in case it has key that array1 doesn't have), and save it all to a new array:
<?php
$arr1 = array(
array('1453274700000',24011),
array('1453275000000',24222),
array('1453276000000',24222), // inexistent in $arr2
);
$arr2 = array(
array('1453275000000',52093),
array('1453274700000',51951),
array('1453273000000',24222), // inexistent in $arr1
);
$arr1dictionary = [];
$arr2dictionary = [];
$result = [];
foreach ($arr1 as $collection) {
$arr1dictionary[$collection[0]] = $collection[1];
}
foreach ($arr2 as $collection) {
$arr2dictionary[$collection[0]] = $collection[1];
}
foreach ($arr1dictionary as $key => $value) {
if (isset($arr2dictionary[$key])) {
$result[$key] = [$key, $value, $arr2dictionary[$key]];
} else {
$result[$key] = [$key, $value, null];
}
}
foreach ($arr2dictionary as $key => $value) {
if (isset($result[$key])) {
continue;
}
$result[$key] = [$key, null, $value];
}
$result = array_values($result);
print_r($result);
Output:
Array
(
[0] => Array
(
[0] => 1453274700000
[1] => 24011
[2] => 51951
)
[1] => Array
(
[0] => 1453275000000
[1] => 24222
[2] => 52093
)
[2] => Array
(
[0] => 1453276000000
[1] => 24222
[2] => (null, the value only exists in $arr1)
)
[3] => Array
(
[0] => 1453273000000
[1] => (null, the value only exists in $arr2)
[2] => 24222
)
)
DEMO

Answer 3

Use array_walk and add second item from $array2 if it exists.
$array1 = array(
array(1453274700000,24011),
array(1453275000000,24222),
array(1453275300000,24284),
array(1453275600000,24331)
);
$array2 = array(
array(1453274700000,51951),
array(1453275000000,52093),
array(1453275300000,52251),
array(1453275600000,52288),
);
array_walk($array1, function(&$item, $key) use ($array2){
if(isset($array2[$key][1])){
$item[] = $array2[$key][1];
}
});
print_r($array1);
Output
Array
(
[0] => Array
(
[0] => 1453274700000
[1] => 24011
[2] => 51951
)
[1] => Array
(
[0] => 1453275000000
[1] => 24222
[2] => 52093
)
[2] => Array
(
[0] => 1453275300000
[1] => 24284
[2] => 52251
)
[3] => Array
(
[0] => 1453275600000
[1] => 24331
[2] => 52288
)
)
EDIT
As #h2ooooooo pointed out that there could be possibility that array items are in random order. If array items can be in random order and they are matched with first index value, use this (works with PHP >= 5.5.0):
$array1 = array(
array(1453274700000,24011),
array(1453275000000,24222),
array(1453275300000,24284),
array(1453275600000,24331),
array(1453276000000,24222) // no match in $array2
);
$array2 = array(
array(1453275000000,52093),
array(1453274700000,51951),
array(1453275300000,52251),
array(1453275600000,52288),
);
array_walk($array1, function(&$item, $key) use ($array2){
// Find match in $array2
$array2_key = array_search($item[0], array_column($array2, 0));
// If match found
if($array2_key !== false && isset($array2[$array2_key][1])){
$item[] = $array2[$array2_key][1];
}
// No match
else{
$item[] = null;
}
});
print_r($array1);
OUTPUT
Array
(
[0] => Array
(
[0] => 1453274700000
[1] => 24011
[2] => 51951
)
[1] => Array
(
[0] => 1453275000000
[1] => 24222
[2] => 52093
)
[2] => Array
(
[0] => 1453275300000
[1] => 24284
[2] => 52251
)
[3] => Array
(
[0] => 1453275600000
[1] => 24331
[2] => 52288
)
[4] => Array
(
[0] => 1453276000000
[1] => 24222
[2] =>
)
)