Combining two arrays with unique field - php

Question

Combining A array and B array and want the result show below
EDITED
a = {
[0]=> array(2) {
["pid"]=> string(1) "1"
["val1"]=> string(1) "1"
}
[1]=> array(2) {
["pid"]=> string(2) "12"
["val1"]=> string(1) "1"
}
[2]=> array(2) {
["pid"]=> string(2) "13"
["val1"]=> string(2) "79"
}
}
b = {
[0]=> array(2) {
["pid"]=> string(1) "1"
["val2"]=> string(1) "1"
}
[1]=> array(2) {
["pid"]=> string(2) "12"
["val2"]=> string(1) "1"
}
[2]=> array(2) {
["pid"]=> string(2) "13"
["val2"]=> string(2) "79"
}
[3]=> array(2) {
["pid"]=> string(2) "61"
["val2"]=> string(1) "1"
}
[4]=> array(2) {
["pid"]=> string(2) "62"
["val2"]=> string(2) "24"
}
}
Need help.

Answer 1

If this is coming from a data source, see if there's a way you can do this outside of PHP (e.g. MySQL's JOIN).
If PHP is your only answer, then below is a solution. Note that I changed the values of val1 and val2 so it was a bit more distinguishable.
You must have some sort of grouping constraint, which is configurable in the script below via $groupByKey. Judging by the common occurrence of PID, I assumed this as the subject key.
Also, if you have more than two arrays all following a similar schema (I have commented out $c as an example), you simply add more arguments to array_merge.
The idea is to keep merging each item in the cumulative list by using a fixed key as a "pointer," if you will.
<?php
$a = array(
array('pid' => 1, 'val1' => 'alpha'),
array('pid' => 3, 'val1' => 'bravo'),
array('pid' => 4, 'val1' => 'charlie')
);
$b = array(
array('pid' => 3, 'val2' => 'delta'),
array('pid' => 5, 'val2' => 'echo'),
array('pid' => 1, 'val2' => 'foxtrot'),
array('pid' => 8, 'val2' => 'golf')
);
/*
$c = array(
array('pid' => 3, 'val3' => 'hotel'),
array('pid' => 5, 'val1' => 'india'),
array('pid' => 1, 'val3' => 'juliette'),
array('pid' => 8, 'val3' => 'kilo')
);
*/
$groupByKey = 'pid'; // this becomes the fixed key
$merged = array_merge($a,$b); // array_merge($a,$b,$c); // cumulative container of all items in every subject array
$result = array(); // the result will be stored here, e.g. a temporary "table"
foreach ( $merged as $item ) { // $merged is essentially a table of subjects and $item is each row
if ( !isset($result[$item[$groupByKey]]) ) { // if we haven't come across this key yet
$result[$item[$groupByKey]] = array(); // initialize it
}
$result[$item[$groupByKey]] = array_merge($result[$item[$groupByKey]],$item); // consolidate all the cells for this row, later duplicate keys will cause values to be replaced
}
$result = array_values($result); // normalize the result keys, for the view they should increment rather than represent the group-by subjects
var_dump($result); // let's see how we did
?>
Provides:
array (size=5)
0 =>
array (size=3)
'pid' => int 1
'val1' => string 'alpha' (length=5)
'val2' => string 'foxtrot' (length=7)
1 =>
array (size=3)
'pid' => int 3
'val1' => string 'bravo' (length=5)
'val2' => string 'delta' (length=5)
2 =>
array (size=2)
'pid' => int 4
'val1' => string 'charlie' (length=7)
3 =>
array (size=2)
'pid' => int 5
'val2' => string 'echo' (length=4)
4 =>
array (size=2)
'pid' => int 8
'val2' => string 'golf' (length=4)