Merging 2 arrays based on a relational array - php

Question

I have the following arrays:
$excel_arr = array(
["C1", "Title 3"],
["A1", "Title 1"],
["B1", "Title 2"],
["D1", "Title 4"]
);
$db_result = array(
"title_2" => "Cell 2 Value",
"title_1" => "Cell 1 Value",
"title_3" => "Cell 3 Value",
"title_5" => "Cell 5 Value"
);
$excel_db_relation = array(
"title_1" => "Title 1",
"title_2" => "Title 2",
"title_3" => "Title 3",
"title_4" => "Title 4",
"title_5" => "Title 5"
);
usort($excel_arr, function ($a, $b) { return strnatcmp($a[0], $b[0]); });
$excel_arr is an array with the titles for each column in an excel file. The first cell defines the cell coordinate and the second the actual cell value.
$db_result is an array containing queried values from a database. The key is column name in the table.
$excel_db_relation is an array which defines the relation between the 2 former arrays. Which excel column is linked to which db table column. In this example they are very similar, but in practice there might be more than just an underscore that differs.
The cell coordinates in $excel_arr defines the order in which each value must be printed. To do this I sort the array with the usort() as seen above.
I need to somehow merge these arrays so that the resulting array becomes:
array("Title 1" => "Cell 1 Value", "Title 2" => "Cell 2 Value", "Title 3" => "Cell 3 Value")
The database array didn't return a value for cell 4 and the excel sheet doesn't define a E5 cell. So these must not be included in the resulting array.
I have tried array_merge($excel_db_relation, $db_result) and various combinations of array_merge() and array_flip() but no matter what I do I can't seem to merge the arrays with "Title X" being the key.

Answer 1

The solution using array_intersect_key, array_intersect and array_column functions:
$result = [];
// getting concurrent 'titles'(by key)
$titles = array_intersect_key($excel_db_relation, $db_result);
foreach (array_intersect($titles, array_column($excel_arr, 1)) as $k => $v) {
$result[$v] = $db_result[$k];
}
print_r($result);
The output:
Array
(
[Title 1] => Cell 1 Value
[Title 2] => Cell 2 Value
[Title 3] => Cell 3 Value
)
Update:
Alternative approach to hold the order in which each value must be printed. Used functions: array_merge_recursive(to combine cell titles and values into separate groups) and array_column functions:
$result = [];
$bindings = array_column(array_merge_recursive($db_result, $excel_db_relation), 0, 1);
foreach (array_column($excel_arr, 1) as $title) {
if (isset($bindings[$title])) $result[$title] = $bindings[$title];
}
print_r($result);
The output:
Array
(
[Title 3] => Cell 3 Value
[Title 1] => Cell 1 Value
[Title 2] => Cell 2 Value
)

Answer 2

Try this:
$result = array_flip($excel_db_relation);
array_walk($result, function(&$value, $key) use ($db_result) {
$value = $db_result[$value];
});
var_dump($result);
But make sure that all keys exist beforehand.

Answer 3

This worked for me:
<?php
//...
usort($excel_arr, function ($a, $b) { return strnatcmp($a[0], $b[0]); });
$result = [];
// traverse the *title* column in the sorted $excel_arr
foreach (array_column($excel_arr, 1) as $a) {
// could use array_flip to speed up this test, though
// this can be problematic if the values aren't *good* array keys
$k = array_search($a, $excel_db_relation);
// if there is a key and it also exists in $db_result
if (false !== $k && array_key_exists($k, $db_result)) {
// assign it to the final result
$result[$a] = $db_result[$k];
}
}
print_r($result);