Removing part of an array from a multidimensional nested array

Question

I've a four levels of nested array like this:

$array = [
    [
        'website' => [
            'id' => 'one'
        ],
        'children' => [
            [
                'website' => [
                    'id' => 'one.one'
                ],
                'children' => [
                    [
                        'website' => [
                            'id' => 'one.one.one'
                        ],
                        'children' => [
                            [
                                'website' => [
                                    'id' => 'one.one.one.one'
                                ],
                                'children' => []
                            ],
                            [
                                'website' => [
                                    'id' => 'one.one.one.two'
                                ],
                                'children' => []
                            ]
                        ]
                    ],
                    [
                        'website' => [
                            'id' => 'one.one.two'
                        ],
                        'children' => [
                            [
                                'website' => [
                                    'id' => 'one.one.two.one'
                                ],
                                'children' => []
                            ],
                            [
                                'website' => [
                                    'id' => 'one.one.two.two'
                                ],
                                'children' => []
                            ]
                        ]
                    ]
                ]
            ],
            [
                'website' => [
                    'id' => 'one.two'
                ],
                'children' => [
                    [
                        'website' => [
                            'id' => 'one.two.one'
                        ],
                        'children' => [
                            [
                                'website' => [
                                    'id' => 'one.two.one.one'
                                ],
                                'children' => []
                            ],
                            [
                                'website' => [
                                    'id' => 'one.two.one.two'
                                ],
                                'children' => []
                            ]
                        ]
                    ],
                    [
                        'website' => [
                            'id' => 'one.two.two'
                        ],
                        'children' => [
                            [
                                'website' => [
                                    'id' => 'one.two.two.one'
                                ],
                                'children' => []
                            ],
                            [
                                'website' => [
                                    'id' => 'one.two.two.two'
                                ],
                                'children' => []
                            ]
                        ]
                    ]
                ]
            ]
        ]
    ]
];

now, I'd like to remove some of the array element based on some rules. For simplicity, let's say, we'd like to remove array elements that has 'id' equals to one.one.two or one.two.one.

I was looking into some answers provided on stackoverflow and was trying to apply them to solve my issue, but didn't go much. The most chalanging thing is to unset part of an array where it's not the farthest point in the array.

I was trying this to note at which level I want to delete the arrays and then trying to unset them using those array index.

$pointer = [];
foreach($array as $key => $level1) {
    $level1pointer = $key;
    $pointer[] = markToDelete($level1, $level1pointer);
    foreach($level1['children'] as $key => $level2) {
        $level2pointer = $key;
        $pointer[] = markToDelete($level2, $level1pointer, $level2pointer);
        foreach($level2['children'] as $key => $level3) {
            $level3pointer = $key;
            $pointer[] = markToDelete($level3, $level1pointer, $level2pointer, $level3pointer);
            foreach($level3['children'] as $key => $level4) {
                $level4pointer = $key;
                $pointer[] = markToDelete($level4, $level1pointer, $level2pointer, $level3pointer, $level4pointer);
            }
        }
    }
}

function markToDelete($array, $level1 = null, $level2 = null, $level3 = null, $level4 = null) {
    $exclusionList = [
        'one.one.two',
        'one.two.one'
    ];

    if (!empty($array['website']) && in_array($array['website']['id'], $exclusionList)) {
        print_r('marking for deletion: '. $array['website']['id'] . PHP_EOL);
        return [
            'id' => $array['website']['id'],
            'level1' => $level1,
            'level2' => $level2,
            'level3' => $level3,
            'level4' => $level4
        ];
    }
    return [];
}

I was also trying to use Iterator like this:

$it = new \RecursiveIteratorIterator(new \RecursiveArrayIterator($array), \RecursiveIteratorIterator::LEAVES_ONLY);
$newArray = [];
foreach($it as $key => $value) {
    $exclusionList = [
        'one.one.two',
        'one.two.one'
    ];
    if(!in_array($value, $exclusionList)) {
        print_r(sprintf('value: %s is ready to be deleted', $value).PHP_EOL);
        $newArray[] = $value;
    }
}

but I need a way to unset the array when looping through the iterator.

I'd like to get an output like this:

$array = [
    [
        'website' => [
            'id' => 'one'
        ],
        'children' => [
            [
                'website' => [
                    'id' => 'one.one'
                ],
                'children' => [
                    [
                        'website' => [
                            'id' => 'one.one.one'
                        ],
                        'children' => [
                            [
                                'website' => [
                                    'id' => 'one.one.one.one'
                                ],
                                'children' => []
                            ],
                            [
                                'website' => [
                                    'id' => 'one.one.one.two'
                                ],
                                'children' => []
                            ]
                        ]
                    ],
                ]
            ],
            [
                'website' => [
                    'id' => 'one.two'
                ],
                'children' => [
                    [
                        'website' => [
                            'id' => 'one.two.two'
                        ],
                        'children' => [
                            [
                                'website' => [
                                    'id' => 'one.two.two.one'
                                ],
                                'children' => []
                            ],
                            [
                                'website' => [
                                    'id' => 'one.two.two.two'
                                ],
                                'children' => []
                            ]
                        ]
                    ]
                ]
            ]
        ]
    ]
];

I'd really appreciate help on how to resolve this in more efficient way. Thanks.

Answer 1

Here's a recursive function that will do what you want. It traverses the array, looking for children whose website id is in the list of ids to be removed and unsetting them. Note that because of your additional top-level array, you need to iterate the function over those values.

function delete_entries(&$array, $ids_to_delete) {
    foreach ($array['children'] as $index => &$child) {
        if (in_array($child['website']['id'], $ids_to_delete)) {
            unset($array['children'][$index]);
        }
        delete_entries($child, $ids_to_delete);
    }
}

foreach ($array as &$arr) {
    delete_entries($arr, array('one.one.two', 'one.two.one'));
}

var_export($array);

The output is as you desire but too long to reproduce here. See the demo on 3v4l.org

Update

The above code won't delete entries on the top level because the array structure is different from lower levels in the array. That can be dealt with in the outer foreach loop:

$excluded = array('two', 'one.one.two', 'one.two.one');
foreach ($array as $key => &$arr) {
    if (in_array($arr['website']['id'], $excluded)) {
        unset($array[$key]);
    }
    else {
        delete_entries($arr, $excluded);
    }
}

Updated demo