Convert multi-dimensional array to flat array php - php

Question

I have a problem in converting multi-dimensional array to flat array
I have an input array like this:
Array
(
[0] => Array
(
[type] => MagentoCatalogRuleModelRuleConditionCombine
[aggregator] => all
[conditions] => Array
(
[0] => Array
(
[type] => MagentoCatalogRuleModelRuleConditionProduct
[attribute] => category_ids
)
)
)
[1] => Array
(
[type] => MagentoCatalogRuleModelRuleConditionProduct
[attribute] => category_ids
)
[2] => Array
(
[type] => MagentoCatalogRuleModelRuleConditionProduct
[attribute] => attribute_set_id
)
)
and I want the output is an array like this, the child array will be flattened as parent array level and it will be recognized by the index:
Array
(
[1--1] => Array
(
[type] => Magento\CatalogRule\Model\Rule\Condition\Combine
[aggregator] => all
)
[1--1--1] => Array
(
[type] => Magento\CatalogRule\Model\Rule\Condition\Product
[attribute] => category_ids
)
[1--2] => Array
(
[type] => Magento\CatalogRule\Model\Rule\Condition\Product
[attribute] => category_ids
)
[1--3] => Array
(
[type] => Magento\CatalogRule\Model\Rule\Condition\Product
[attribute] => attribute_set_id
)
)
the input array may contain many child layers and the output array must be index in that format.
I'm stucking to write this logic into code. Thank you!

Answer 1

You can use a recursive function like this:
function flatten($array, $parent_key = '1') {
$flattened_array = [];
foreach ($array as $key => $item) {
$tmp = $item;
unset($tmp['conditions']);
$child_key = $parent_key . '--' . strval($key + 1);
$flattened_array[$child_key] = $tmp;
if (isset($item['conditions'])) {
$flattened_array = array_merge($flattened_array, flatten($item['conditions'], $child_key));
}
}
return $flattened_array;
}
$input = [
0 => [
'type' => 'MagentoCatalogRuleModelRuleConditionCombine',
'aggregator' => 'all',
'conditions' => [
0 => [
'type' => 'MagentoCatalogRuleModelRuleConditionProduct',
'attribute' => 'category_ids'
]
]
],
1 => [
'type' => 'MagentoCatalogRuleModelRuleConditionProduct',
'attribute' => 'category_ids'
],
2 => [
'type' => 'MagentoCatalogRuleModelRuleConditionProduct',
'attribute' => 'attribute_set_id'
]
];
print_r(flatten($input));
Output:
Array
(
[1--1] => Array
(
[type] => MagentoCatalogRuleModelRuleConditionCombine
[aggregator] => all
)
[1--1--1] => Array
(
[type] => MagentoCatalogRuleModelRuleConditionProduct
[attribute] => category_ids
)
[1--2] => Array
(
[type] => MagentoCatalogRuleModelRuleConditionProduct
[attribute] => category_ids
)
[1--3] => Array
(
[type] => MagentoCatalogRuleModelRuleConditionProduct
[attribute] => attribute_set_id
)
)