Transform a 3-dimensional array in PHP - php

Question

I have an array like this :
array(3) {
["FL_1"] => array(3) {
["MIC_1"] => array(1) {
["SP_4"] => float(7)
}
["MIC_13"] => array(1) {
["SP_16"] => float(4)
}
["MIC_6"] => array(1) {
["SP_74"] => float(4)
}
}
["FL_2"] => array(2) {
["MIC_1"] => array(1) {
["SP_5"] => float(4)
}
["MIC_13"] => array(1) {
["SP_17"] => float(4)
}
["MIC_6"] > array(1) {
["SP_75"] => float(4)
}
}
["FL_3"] => array(2) {
["MIC_1"] => array(1) {
["SP_5"] => float(89)
}
["MIC_13"] => array(1) {
["SP_18"] => float(1)
}
["MIC_6"] > array(1) {
["SP_78"] => float(21)
}
}
}
For each FL_X, I need to keep only one MIC_X that follow the conditions below :
1- This MIC_X needs to be the same for each FL_X
2- This MIC_X needs to have the lowest possible SP_Xvalue
From this example I need to get the following array
array(3) {
["FL_1"] => array(1) {
["MIC_13"] => array(1) {
["SP_16"] => float(4)
}
}
["FL_2"] => array(1) {
["MIC_13"] => array(1) {
["SP_17"] => float(6)
}
}
["FL_3"] => array(1) {
["MIC_13"] => array(1) {
["SP_18"] => float(1)
}
}
}
Any help on how to do this would be much appreciated.
Thank you !

Answer 1

Here's one possible solution. It uses array_walk_recursive to find the SP_X key associated with the minimum SP_X value, then it traverses the array to find the MIC_X key associated with that SP_X key and value, and finally it uses array_map and array_filter to extract only those MIC_X key values from the original array:
// find the minimum SP_X value and its key
$min_sp = PHP_INT_MAX;
$min_key = '';
array_walk_recursive($array, function ($v, $k) use (&$min_sp, &$min_key) {
if ($v < $min_sp) {
$min_sp = $v;
$min_key = $k;
}
});
// find the MIC_X key corresponding to the min SP_X value
$mic_key = '';
foreach ($array as $fl) {
foreach ($fl as $mic => $sp) {
if (isset($sp[$min_key]) && $sp[$min_key] == $min_sp) {
$mic_key = $mic;
break 2;
}
}
}
// filter the array to get all the MIC_X values
$out = array_map(function ($fl) use ($mic_key) {
return array_filter($fl, function ($mic) use ($mic_key) {
return $mic == $mic_key;
}, ARRAY_FILTER_USE_KEY);
}, $array);
print_r($out);
Output:
Array
(
[FL_1] => Array
(
[MIC_13] => Array
(
[SP_16] => 4
)
)
[FL_2] => Array
(
[MIC_13] => Array
(
[SP_17] => 4
)
)
[FL_3] => Array
(
[MIC_13] => Array
(
[SP_18] => 1
)
)
)
Demo on 3v4l.org