Merge values in foreach loop based on preg match condition - php

Question

I have been trying unsuccessfully to access and manipulate certain name value pairs within an array when in a foreach loop.
My data is in an array like this:
[0] => Array
(
[subject] => math
[price] => 5
[year] => 2006
)
[1] => Array
(
[subject] => reading
[price] => 7
[year] => 2007
[author] => Smith
[publisher] => Press
)
[2] => Array
(
[subject] => reading
[price] => 9
[year] => 2008
[author] => Jones
[copyright] => 1999
)
My code is:
$count = count($array);
for ($i = 0; $i < $count; $i++) {
foreach($array[$i] as $name => $value) {
if(preg_match('(subject|price|year)', $name) != 1) {
#$desc .= '-'.$name.'-'.$value;
} else {
$desc = '';
}
echo $i.' : '.$desc.'<br />';
}
}
My desired output from the code above would be:
0 : subject-math / price-5 / year-2006
1 : subject-reading / price-7 / year-2007 / author-Smith-publisher-Press
2 : subject-reading / price-9 / year-2008 / author-Jones-copyright-1999
The main issue I am facing is that I don't know how to combine & echo out all of the name value pairs that don't match the preg_match condition. Essentially subject, price and year and common to every record but any of the others I want to be able to access all merged together as one item.
Thanks in advance for any help!

Answer 1

This code will do what you want. It loops through your array, pushing all the key-value pairs into an array and then echo'ing an implode (with /) of the array. Values for subject, price and year have their own entries, while all other values are pushed into an array which is then also imploded using - to give your desired output. Rather than using preg_match to match keys, a simple in_array is used instead:
foreach ($data as $k => $d) {
$out = array();
foreach ($d as $key => $value) {
if (in_array($key, ['subject', 'price', 'year'])) {
$out[] = "$key-$value";
}
else {
$out['others'][] = "$key-$value";
}
}
if (isset($out['others'])) $out[] = implode('-', $out['others']);
unset($out['others']);
echo "$k : " . implode(' / ', $out) . "\n";
}
Output:
0 : subject-math / price-5 / year-2006
1 : subject-reading / price-7 / year-2007 / author-Smith-publisher-Press
2 : subject-reading / price-9 / year-2008 / author-Jones-copyright-1999
Demo on 3v4l.org

Answer 2

I guess, it'll be the most simple implementation:
foreach ($array as $index => $item)
{
$result = array_filter
([
'subject-' . array_shift($item),
'price-' . array_shift($item),
'subject-' . array_shift($item),
implode('-', $item)
]);
$result = implode(' / ', $result);
echo "$index: $result\n";
}