PHP - get unique values in while loop - php

Question

I have the following code:-
if( $featured_query->have_posts() ): $property_increment = 0;
while( $featured_query->have_posts() ) : $featured_query->the_post();
$town = get_field('house_town');
$a = array($town);
$b = array_unique($a);
sort($b);
var_dump($b);
$property_increment++; endwhile; ?>
<?php endif; wp_reset_query();
var_dump(b) shows:-
array(1) { [0]=> string(10) "Nottingham" } array(1) { [0]=> string(9) "Leicester" } array(1) { [0]=> string(9) "Leicester" } array(1) { [0]=> string(11) "Mountsorrel" } array(1) { [0]=> string(12) "Loughborough" } array(1) { [0]=> string(12) "Loughborough" }
var_dump($town) shows:-
string(10) "Nottingham" string(9) "Leicester" string(9) "Leicester" string(11) "Mountsorrel" string(12) "Loughborough" string(12) "Loughborough"
var_dump($a) shows:-
array(1) { [0]=> string(10) "Nottingham" } array(1) { [0]=> string(9) "Leicester" } array(1) { [0]=> string(9) "Leicester" } array(1) { [0]=> string(11) "Mountsorrel" } array(1) { [0]=> string(12) "Loughborough" } array(1) { [0]=> string(12) "Loughborough" }
What I want to do is get the unique vales of $town and output them into a select option:-
<select>
<option value="Leicester">Leicester</option>';
<option value="Loughborough">Loughborough</option>';
<option value="Mountsorrel">Mountsorrel</option>';
</select>';
In alpha as above, any help would be much appreciated.

Answer 1

#collect all get_field('house_town') in while
$collect[] = get_field('house_town');
#then do the work
$html = implode('',
array_map(
function($a){
return "<option value='{$a}'>{$a}</option>";
},
array_unique($collect)
)
);

Answer 2

Your array needs to be un-nested with array_column before you sort it and make it unique. So after you initialised $a, continue like this:
$b = array_unique(array_column($a, 0));
sort($b);
and then make the HTML:
$html = "";
foreach($b as $town) {
$html .= "<option value='$town'>$town</option>";
}
echo "<select>$html</select>";
If you don't have array_column, then you can use this replacement:
function array_column($arr, $column) {
$res = array();
foreach ($arr as $el) {
$res[] = $el[$column];
}
return $res;
}

Answer 3

Here's a summary of Chris G's comment and trincot's code snippet for generating the HTML code.
Note: for testing purposes I have created the $town array manually here. Replace it by your statement $town = get_field('house_town');
<?php
$town = array(
"Nottingham",
"Leicester",
"Leicester",
"Mountsorrel",
"Loughborough",
"Loughborough"
);
// $town = get_field('house_town');
$html = "";
$town = array_unique($town);
sort($town);
foreach($town as $xtown) {
$html .= "<option value='$xtown'>$xtown</option>";
}
echo "<select>$html</select>";
?>

Answer 4

Basic/ General unique usage in while/ foreach loop
// refer to
$a = array($town); // $a in while/ foreach loop
if(current($a) != next($a)) {
// do your query here // get required unique here
}
// Note: caring and sharing