Creating a dynamic hierarchical array in PHP - php

Question

I have this general data structure:
$levels = array('country', 'state', 'city', 'location');
I have data that looks like this:
$locations = array(
1 => array('country'=>'USA', 'state'=>'New York', 'city'=>'NYC', 'location'=>'Central Park', 'count'=>123),
2 => array('country'=>'Germany', ... )
);
I want to create hierarchical arrays such as
$hierarchy = array(
'USA' => array(
'New York' => array(
'NYC' => array(
'Central Park' => 123,
),
),
),
'Germany' => array(...),
);
Generally I would just create it like this:
$final = array();
foreach ($locations as $L) {
$final[$L['country']][$L['state']][$L['city']][$L['location']] = $L['count'];
}
However, it turns out that the initial array $levels is dynamic and can change in values and length So I cannot hard-code the levels into that last line, and I do not know how many elements there are. So the $levels array might look like this:
$levels = array('country', 'state');
Or
$levels = array('country', 'state', 'location');
The values will always exist in the data to be processed, but there might be more elements in the processed data than in the levels array. I want the final array to only contain the values that are in the $levels array, no matter what additional values are in the original data.
How can I use the array $levels as a guidance to dynamically create the $final array?
I thought I could just build the string $final[$L['country']][$L['state']][$L['city']][$L['location']] with implode() and then run eval() on it, but is there are a better way?

Answer 1

Here's my implementation. You can try it out here:
$locations = array(
1 => array('country'=>'USA', 'state'=>'New York', 'city'=>'NYC', 'location'=>'Central Park', 'count'=>123),
2 => array('country'=>'Germany', 'state'=>'Blah', 'city'=>'NY', 'location'=>'Testing', 'count'=>54),
);
$hierarchy = array();
$levels = array_reverse(
array('country', 'state', 'city', 'location')
);
$lastLevel = 'count';
foreach ( $locations as $L )
{
$array = $L[$lastLevel];
foreach ( $levels as $level )
{
$array = array($L[$level] => $array);
}
$hierarchy = array_merge_recursive($hierarchy, $array);
}
print_r($hierarchy);

Answer 2

Cool question. A simple approach:
$output = []; //will hold what you want
foreach($locations as $loc){
$str_to_eval='$output';
for($i=0;$i<count($levels);$i++) $str_to_eval .= "[\$loc[\$levels[$i]]]";
$str_to_eval .= "=\$loc['count'];";
eval($str_to_eval); //will build the array for this location
}
Live demo

Answer 3

If your dataset always in fixed structure, you might just loop it
$data[] = [country=>usa, state=>ny, city=>...]
to
foreach ($data as $row) {
$result[][$row[country]][$row[state]][$row[city]] = ...
}
In case your data is dynamic and the levels of nested array is also dynamic, then the following is an idea:
/* convert from [a, b, c, d, ...] to [a][b][...] = ... */
function nested_array($rows, $level = 1) {
$data = array();
$keys = array_slice(array_keys($rows[0]), 0, $level);
foreach ($rows as $r) {
$ref = &$data[$r[$keys[0]]];
foreach ($keys as $j => $k) {
if ($j) {
$ref = &$ref[$r[$k]];
}
unset($r[$k]);
}
$ref = count($r) > 1 ? $r : reset($r);
}
return $data;
}

Answer 4

try this:
<?php
$locations = [
['country'=>'USA', 'state'=>'New York', 'city'=>'NYC', 'location'=>'Central Park', 'street'=>'7th Ave', 'count'=>123],
['country'=>'USA', 'state'=>'Maryland', 'city'=>'Baltimore', 'location'=>'Harbor', 'count'=>24],
['country'=>'USA', 'state'=>'Michigan', 'city'=>'Lansing', 'location'=>'Midtown', 'building'=>'H2B', 'count'=>7],
['country'=>'France', 'state'=>'Sud', 'city'=>'Marseille', 'location'=>'Centre Ville', 'count'=>12],
];
$nk = array();
foreach($locations as $l) {
$jsonstr = json_encode($l);
preg_match_all('/"[a-z]+?":/',$jsonstr,$e);
$narr = array();
foreach($e[0] as $k => $v) {
if($k == 0 ) {
$narr[] = '';
} else {
$narr[] = ":{";
}
}
$narr[count($e[0]) -1] = ":" ;
$narr[] = "";
$e[0][] = ",";
$jsonstr = str_replace($e[0],$narr,$jsonstr).str_repeat("}",count($narr)-3);
$nk [] = $ko =json_decode($jsonstr,TRUE);
}
print_r($nk);

Answer 5

Database have three field:
here Name conatin contry state and city name
id,name,parentid
Pass the contry result to array to below function:
$data['contry']=$this->db->get('contry')->result_array();
$return['result']=$this->ordered_menu( $data['contry'],0);
echo "<pre>";
print_r ($return['result']);
echo "</pre>";
Create Function as below:
function ordered_menu($array,$parent_id = 0)
{
$temp_array = array();
foreach($array as $element)
{
if($element['parent_id']==$parent_id)
{
$element['subs'] = $this->ordered_menu($array,$element['id']);
$temp_array[] = $element;
}
}
return $temp_array;
}