Split and parse a string to create an array of associative arrays

Question

How can I convert the following string into two dimensional array?

$coordinates = "9.499819 123.920318,9.490845 123.916563,9.484644 123.922292,9.49148 123.931519,9.499755 123.925683,9.499819 123.920318";

I want to separate pairs of values using the commas, then separate each pair by their delimiting space to form associative rows containing float-type values.

Desired Output:

$polygon = array(
    array('lat' => 9.499819, 'lng' => 123.920318),
    array('lat' => 9.490845, 'lng' => 123.916563),
    array('lat' => 9.484644, 'lng' => 123.922292),
    array('lat' => 9.49148, 'lng' => 123.931519),
    array('lat' => 9.499755, 'lng' => 123.925683),
    array('lat' => 9.499819, 'lng' => 123.920318)
);

Answer 1

For a new contributor, a solution with foreach is easier to understand in my opinion. The steps are commented in the code.

$coordinates = "9.499819 123.920318,9.490845 123.916563,9.484644 123.922292,9.49148 123.931519,9.499755 123.925683,9.499819 123.920318";

$polygon = explode(',',$coordinates);
/*
array (
  0 => "9.499819 123.920318",
  1 => "9.490845 123.916563",
*/

foreach($polygon as $index => $latLng){
  //The element $latLng is split into two variables with list and explode.
  list($lat,$lng) = explode(' ',$latLng);

  //The elements are replaced by a new array with the variables $lat and $lng as float
  $polygon[$index] = ['lat' => (float)$lat, 'lng' => (float)$lng];
}

//test output
echo '<pre>';
var_export($polygon);

output:

array (
  0 => 
  array (
    'lat' => 9.499819,
    'lng' => 123.920318,
  ),
  1 => 
  array (
    'lat' => 9.490845,
    'lng' => 123.916563,
  ),
  2 => 
  array (
    'lat' => 9.484644,
    'lng' => 123.922292,
  ),
  3 => 
  array (
    'lat' => 9.49148,
    'lng' => 123.931519,
  ),
  4 => 
  array (
    'lat' => 9.499755,
    'lng' => 123.925683,
  ),
  5 => 
  array (
    'lat' => 9.499819,
    'lng' => 123.920318,
  ),
) 

Add 2022-03-04:

This one-liner with preg_match_all already returns the complete result, but with additional numeric keys.

preg_match_all('~(?<lat>[0-9.]+) (?<lng>[0-9.]+),?~', $coordinates, $match,PREG_SET_ORDER);

array_map can be used to remove the superfluous values.

$polygon = array_map(
  function($row){return ['lat' => $row['lat'],'lng' => $row['lng']];},
  $match
);