php sort merge arrays

Question

I have a list of (xml) items, each item has a category and a name:

Category | Name

1         |  Joe
2         |  Carol
3         |  Bruce
1         |  Michael     
1         |  Alan
2         |  Brian

I want to sort the names ascending within categories descending like so:

Category | Name

3         |  Bruce
2         |  Brian
2         |  Carol
1         |  Alan
1         |  Joe
1         |  Michael

with the aim of creating a Select dropdown on a web page with each category as an OptGroup and the names sorted within the OptGroup. I have very little experience with PHP, I think I need to sort merge arrays, but after many hours trying to understand how to, I'm not making much progress. Any help greatly appreciated

no you do not need to separate them, just create a multi dimensional arrray from those xml — Kevin, Oct 01 '14 at 07:45
Convert the XML to an array and then check the `asort()` function of PHP. At least show us the tries you've made so far. — TiMESPLiNTER, Oct 01 '14 at 10:13

Pankaj katiyar · Answer 1 · 2014-10-01T12:17:34.637

1

$data[] = array('category' => 1, 'name' => 'Joe');
$data[] = array('category' => 2, 'name' => 'Carol');
$data[] = array('category' => 3, 'name' => 'Bruce');
$data[] = array('category' => 1, 'name' => 'Michael');
$data[] = array('category' => 1, 'name' => 'Alan');
$data[] = array('category' => 2, 'name' => 'Brian');


<?php
// Obtain a list of columns
$category =array();
$name =array();
foreach ($data as $key => $row) {
    $category[$key]  = $row['category'];
    $name[$key] = $row['name'];
}

// Sort the data with category descending, name ascending
// Add $data as the last parameter, to sort by the common key
array_multisort($category, SORT_DESC, $name, SORT_ASC, $data);
echo '<pre>'; print_r($category);
?>

edited Oct 01 '14 at 12:17

answered Oct 01 '14 at 09:28

Pankaj katiyar

464
10
26

Thanks Pankaj for your time & help. The array_multisort gave this Warning: array_multisort(): Argument #1 is expected to be an array or a sort flag. this is what I have in a foreach loop $expld = explode("_", $title); $data[$cnt]['category'] = $expld[0]; $data[$cnt]['name'] = expld[1]; $cnt++; – user3229980 Oct 01 '14 at 11:43
initialize $category =array(); $name =array(); – Pankaj katiyar Oct 01 '14 at 12:12
You could at least credit the [documentation example you adapted for this](http://php.net/manual/en/function.array-multisort.php). – Martijn Pieters Sep 21 '17 at 13:01

score 0 · Answer 2 · answered Oct 01 '14 at 17:54

Hi thanks to everybody for your help including all the other Stackoverflow questions which I googled to piece this together, not sure how I did it, bit of a case of an infinite number of monkeys or should that be newbies, anways here's what worked for me. Sorts names ascending within contributions descending

function compare($a, $b) {
    if ($a['contribution'] == $b['contribution']) {
       return ($a['name'] < $b['name']) ? -1 : 1;
    } else {
       return ($b['contribution'] - $a['contribution']);
    }
}    
usort($ads_by_cotribution, 'compare');

It's all magic to me, that's the beauty of it. I didn't include the case of names being equal 'cause there shouldn't be any and as I understand equal values would still stay together just in a different order. I'd like to understand how these functions work, do they continuously walk through the array until there's no change in the order - what we used to call a bubble sort? Does ($b['contribution'] - $a['contribution']) indicate which is the larger? Finley is there a difference between sorting contributions - a numeric field and names - an alpha field?

score -1 · Answer 3 · edited Oct 01 '14 at 08:03

-1

$name = array("Joe", "Carol", "Bruce", "Michael","Alan","Brian");
sort($name);

php-in built function sort will produce desire result

edited Oct 01 '14 at 08:03

Kartoch

7,610
9
40
68

answered Oct 01 '14 at 07:46

Pankaj katiyar

464
10
26

Where are the categories that the names are sorted within? – user3229980 Oct 01 '14 at 08:11
Can I have an example of how to insert $category and $name into an array, thanks – user3229980 Oct 01 '14 at 08:28
This post can help you http://stackoverflow.com/questions/6578832/how-to-convert-xml-into-array-in-php – Pankaj katiyar Oct 01 '14 at 08:56

php sort merge arrays

Category | Name

Category | Name

3 Answers3