php remove empty 'columns' in multidimensional, associative array - php

Question

Goal: Generate an array that includes only those 'columns' with data, even though a 'header' may exist.
Example Data:
Array (
[HeaderRow] => Array (
[0] => Employee [1] => LaborHours [2] => 0.1 [3] => 0.25 [4] => 0.5 [5] => 0.8
)
[r0] => Array (
[0] => Joe [1] => 5 [2] => [3] => [4] => 50 [5] =>
)
[r1] => Array (
[0] => Fred [1] => 5 [2] => 10 [3] => [4] => [5] =>
)
)
Desired Output:
Array (
[HeaderRow] => Array (
[0] => Employee [1] => LaborHours [2] => 0.1 [4] => 0.5
)
[r0] => Array (
[0] => Joe [1] => 5 [2] => [4] => 50
)
[r1] => Array (
[0] => Fred [1] => 5 [2] => 10 [4] =>
)
)
So, in this very dumbed down example, the HeaderRow will always have data, but if both c0 and c1 are empty (as is the case for [3] and [5]) then I want to remove. I tried iterating through with for loops like I would in other languages, but that apparently doesn't work with associative arrays. I then tried doing a transpose followed by two foreach loops, but that failed me as well. Here's a sample of my for loop attempt:
Attempt with For Loop
for ($j = 0; $j <= count(reset($array))-1; $j++) {
$empty = true;
for ($i = 1; $i <= count($array)-1; $i++) {
if(!empty($array[$i][$j])) {
$empty = false;
break;
}
}
if ($empty === true)
{
for ($i = 0; $i <= count($array); $i++) {
unset($array[$i][$j]);
}
}
}
return $array;
Attempt with transpose:
$array = transpose($array);
foreach ($array as $row)
{
$empty = true;
foreach ($row as $value)
{
if (!empty($value))
{
$empty = false;
}
}
if ($empty) {
unset($array[$row]);
}
}
$array = transpose($array);
return $array;
function transpose($arr) {
$out = array();
foreach ($arr as $key => $subarr) {
foreach ($subarr as $subkey => $subvalue) {
$out[$subkey][$key] = $subvalue;
}
}
return $out;
}
I know the transpose one isn't terribly fleshed out, but I wanted to demonstrate the attempt.
Thanks for any insight.

Answer 1

We can make this more simpler. Just get all column values using array_column.
Use array_filter with a custom callback to remove all empty string values.
If after filtering, size of array is 0, then that key needs to be unset from all
subarrays.
Note: The arrow syntax in the callback is introduced since PHP 7.4.
Snippet:
<?php
$data = array (
'HeaderRow' => Array (
'0' => 'Employee','1' => 'LaborHours', '2' => 0.1, '3' => 0.25, '4' => 0.5, '5' => 0.8
),
'r0' => Array (
'0' => 'Joe', '1' => 5, '2' => '','3' => '', '4' => 50, '5' => ''
),
'r1' => Array (
'0' => 'Fred', '1' => 5,'2' => 10, '3' => '', '4' => '', '5' => ''
)
);
$cleanup_keys = [];
foreach(array_keys($data['HeaderRow']) as $column_key){
$column_values = array_column($data, $column_key);
array_shift($column_values); // removing header row value
$column_values = array_filter($column_values,fn($val) => strlen($val) != 0);
if(count($column_values) == 0) $cleanup_keys[] = $column_key;
}
foreach($data as &$row){
foreach($cleanup_keys as $ck){
unset($row[ $ck ]);
}
}
print_r($data);

Answer 2

It figures, I work on this for a day and have a moment of clarity right after posting. The answer was that I wasn't leveraging the Keys.:
function array_cleanup($array)
{
$array = transpose($array);
foreach ($array as $key => $value)
{
$empty = true;
foreach ($value as $subkey => $subvalue)
{
if ($subkey != "HeaderRow") {
if (!empty($subvalue))
{
$empty = false;
}
}
}
if ($empty) {
unset($array[$key]);
}
}
$array = transpose($array);
return $array;
}