Removing duplicates from merged array - php

Question

I've been doing here some name processor, and I've run into small, kind of noob-ish problem.
I have CSV file with names and status, filters them only by 'Cool Ones" status, then i'm querying SQL, and getting another list of names that i have entered manually.
So here is code example, where i'm taking CSV file, filter, querying SQL, then it creates array, merges it and sorts alphabetically.
$nameFile = "names/$eid.csv";
$content = array_map('str_getcsv', file($nameFile));
$filteredData = array_filter($content, function($v){
return $v['1'] === 'Cool Ones'; },ARRAY_FILTER_USE_BOTH); //because in this file there are also 'Not Cool Ones'
$freePeople = array();
$sth = $DBcon->prepare("SELECT guestName, guestType FROM guestList WHERE forEvent = '$eid' ORDER BY 'guestName'");
$sth->execute();
$result2 = $sth->fetchAll(PDO::FETCH_NUM);
$listNames = array();
foreach($result2 as $row) {
$listNames[] = $row['0'];
$freeGuestName = $row['0'];
$freeGuestType = $row['1'];
}
$merged = array_merge($filteredData, $result2);
$sortedGuests = usort($merged, "sortGuestNames");
so my problem lies, that when outputing array, I'm getting duplicate results,
[50] => Array
(
[0] => John Down
[1] => Best Ones
)
[51] => Array
(
[0] => John Down
[1] => Cool Ones
)
Dunno what's next - i want that if my queried name is same as in this first CSV file, then hide this one, and show mine.
i was trying to unset key with
foreach($merged[$i]['0'] as $key => $value) {
if (in_array($merged[$i]['0'], $value)) {
unset($merged[$i]['0'][$key]);
}
}
but no luck, still outputing duplicates.
You can suggest better approach.
I've thought - maybe open CSV, query SQL and find my manual names - look up in opened CSV fields, append my status there, merge and push them to SQL database or new CSV file, where it could be outputted.
Thanks a lot!

Answer 1

A few things,
The thing we need to do is merge both arrays, but control which one overwrites the other. I am not sure if what you have does that now (in a reliable way) but one way to do that is to build 2 arrays. Both with the same structure, and the key as your unique field so we want this:
$csv = ['John Down' => ['John Down','Best Ones']];
$db = ['John Down' => ['John Down','Cool Ones']];
Then when we do array merge, the second argument will overwrite the first. So if we do
$csv = ['John Down' => ['John Down','Best Ones']];
$db = ['John Down' => ['John Down','Cool Ones']];
print_r(array_merge($csv, $db));
echo "\n";
print_r(array_merge($db, $csv));
Output:
// print_r(array_merge($csv, $db));
Array
(
[John Down] => Array
(
[0] => John Down
[1] => Cool Ones
)
)
//print_r(array_merge($db, $csv))
Array
(
[John Down] => Array
(
[0] => John Down
[1] => Best Ones
)
)
Sandbox
As you can see we can control which array is overwritten by the order we send them to array_merge in. The second one (or right one) overwrites the one to the left. So simply it reads from left to right.
So now what's the easiest way to get that structure from the DB? In PDO we can use FETCH_GROUP which takes the first column in the query and uses it as the top level key.
$sth = $DBcon->prepare("SELECT guestName, guestType FROM guestList WHERE forEvent = :eid GROUP BY guestName ORDER BY guestName");
//-- add `GROUP BY guestName` we don't want duplicates anyway
//-- no quotes see: ... ORDER BY 'guestName');
//-- use prepared statements
$sth->execute(['eid'=>$eid]);
$result2 = $sth->fetchAll(PDO::FETCH_NUM);
$result2 = array_column($result2, null, 0);
For the CSV you can build it that way when you read the file (by adding the key) and using fgetcsv or you can use this trick (also used above):
$csv = [['John Down','Best Ones']];
print_r(array_column($csv, null, 0));
Output
Array
(
[John Down] => Array
(
[0] => John Down
[1] => Best Ones
)
)
Sandbox
Which should give you basically what we need, then it's a simple matter of using array_merge.
One thing to mention is if your DB or CSV are not unique, you'll get some duplicate removal there too, you may have to account for.
Removing duplicates is fine, but you want to make sure to remove the correct duplicates in a repeatable and robust way. Using array_merge we can control that no mater the order the rows come in from the DB and the file.
Summery
So if we put this all together, this is all you should need:
$nameFile = "names/$eid.csv";
$content = array_map('str_getcsv', file($nameFile));
$filteredData = array_filter($content, function($v){
return $v['1'] === 'Cool Ones';
},ARRAY_FILTER_USE_BOTH); //because in this file there are also 'Not Cool Ones'
$sth = $DBcon->prepare("SELECT guestName, guestType FROM guestList WHERE forEvent = :eid GROUP BY guestName ORDER BY guestName");
$sth->execute(['eid'=>$eid]);
$result2 = $sth->fetchAll(PDO::FETCH_NUM);
$listNames = array_column($result2, 0);
$merged = array_merge(array_column($filteredData, null, 0), array_column($result2, null, 0));
$sortedGuests = usort($merged, "sortGuestNames");
So instead of adding code in patching over an issue, we went to the root cause and fixed it there and reduced the code by a few lines. This will work provided your CSV is in the correct format. guestName, guestType
Cheers!
http://php.net/manual/en/function.array-column.php
array_column ( array $input , mixed $column_key [, mixed $index_key = NULL ] ) : array
array_column() returns the values from a single column of the input, identified by the column_key. Optionally, an index_key may be provided to index the values in the returned array by the values from the index_key column of the input array.
input A multi-dimensional array or an array of objects from which to pull a column of values from. If an array of objects is provided, then public properties can be directly pulled. In order for protected or private properties to be pulled, the class must implement both the __get() and __isset() magic methods.
column_key The column of values to return. This value may be an integer key of the column you wish to retrieve, or it may be a string key name for an associative array or property name. It may also be NULL to return complete arrays or objects (this is useful together with index_key to reindex the array).
index_key The column to use as the index/keys for the returned array. This value may be the integer key of the column, or it may be the string key name. The value is cast as usual for array keys (however, objects supporting conversion to string are also allowed).

Answer 2

Assuming that you need unique user name, following is the solution.
Create a new blank users array.
Loop over the users array.
Append the users to new users array.
The key should be user name.
Hence, every time the same user comes, he will overwrite the previous one, removing duplicate.
Code:
$users = [
['John Down', 'Best Ones'],
['John Down', 'Cool Ones']
];
$newUsers = [];
if (! empty($users)) {
foreach ($users as $user) {
$newUsers[$user[0]] = $user[1];
}
}
echo '<pre>';print_r($newUsers);echo '</pre>';
// Output:
Array
(
[John Down] => Cool Ones
)

Answer 3

I solved my case:
I removed second key from merged array, then unserialize it, and mapped only unique ones! Everything is now working!
$input = array_map("unserialize", array_unique(array_map("serialize", $merged)));
Sometimes i really enjoy asking help for you, because it makes me think! To think deeper than ussual.