array tree of objects into assotiative array with levels

Question

I have tree of objects:

array(4) (
    0 => object stdClass(14) {
        public id => string(1) "1"
        public parent_id => string(1) "0"
        public name => string(18) "Stationary engines"
        public uri => string(18) "stationary-engines"
        public created => string(19) "2012-11-19 15:15:34"
        public updated => NULL
        public subcategories => array(4) (
            0 => object stdClass(14) {
                public id => string(1) "5"
                public parent_id => string(1) "1"
                public name => string(6) "Yanmar"
                public uri => string(6) "yanmar"
                public created => string(19) "2012-11-19 15:23:36"
                public updated => NULL
                public subcategories => array(1) (
                    0 => object stdClass(14) {
                        public id => string(2) "15"
                        public parent_id => string(1) "5"
                        public name => string(18) "Yanmar subcategory"
                        public uri => string(18) "yanmar-subcategory"

                        public created => string(19) "2012-11-21 16:38:06"
                        public updated => NULL
                        public subcategories => array(1) (
                            0 => object stdClass(13) {
                                public id => string(2) "16"
                                public parent_id => string(2) "15"
                                public name => string(30) "Yanmar subcategory subcategory"
                                public uri => string(30) "yanmar-subcategory-subcategory"
                                public created => string(19) "2012-11-21 17:37:00"
                                public updated => NULL
                            }
                        )
                    }
                )
            }
            1 => object stdClass(13) {
                public id => string(1) "6"
                public parent_id => string(1) "1"
                public name => string(11) "Мercruiser"
                public uri => string(10) "mercruiser"
                public created => string(19) "2012-11-19 15:23:36"
                public updated => NULL
            }
            2 => object stdClass(13) {
                public id => string(1) "7"
                public parent_id => string(1) "1"
                public name => string(11) "Volvo-Penta"
                public uri => string(11) "volvo-penta"
                public created => string(19) "2012-11-19 15:24:49"
                public updated => NULL
            }
            3 => object stdClass(13) {
                public id => string(1) "8"
                public parent_id => string(1) "1"
                public name => string(27) "Basic configuration engines"
                public uri => string(27) "basic-configuration-engines"
                public created => string(19) "2012-11-19 15:24:49"
                public updated => NULL
            }
        )
    }
    1 => object stdClass(14) {
        public id => string(1) "2"
        public parent_id => string(1) "0"
        public name => string(10) "Generators"
        public uri => string(10) "generators"
        public created => string(19) "2012-11-19 15:15:58"
        public updated => NULL
        public subcategories => array(4) (
            0 => object stdClass(13) {
                public id => string(1) "9"
                public parent_id => string(1) "2"
                public name => string(6) "Diesel"
                public uri => string(6) "diesel"
                public created => string(19) "2012-11-19 15:34:38"
                public updated => NULL
            }
            1 => object stdClass(13) {
                public id => string(2) "10"
                public parent_id => string(1) "2"
                public name => string(8) "Gasoline"
                public uri => string(8) "gasoline"
                public created => string(19) "2012-11-19 15:34:38"
                public updated => NULL
            }
            2 => object stdClass(13) {
                public id => string(2) "11"
                public parent_id => string(1) "2"
                public name => string(6) "Kohler"
                public uri => string(6) "kohler"
                public created => string(19) "2012-11-19 15:35:35"
                public updated => NULL
            }
            3 => object stdClass(13) {
                public id => string(2) "12"
                public parent_id => string(1) "2"
                public name => string(13) "Fischer Panda"
                public uri => string(13) "fischer-panda"
                public created => string(19) "2012-11-19 15:36:14"
                public updated => NULL
            }
        )
    }
    2 => object stdClass(14) {
        public id => string(1) "3"
        public parent_id => string(1) "0"
        public name => string(14) "Boat equipment"
        public uri => string(14) "boat-equipment"
        public created => string(19) "2012-11-19 15:16:59"
        public updated => NULL
        public subcategories => array(1) (
            0 => object stdClass(13) {
                public id => string(2) "13"
                public parent_id => string(1) "3"
                public name => string(11) "Subcategory"
                public uri => string(11) "subcategory"
                public created => string(19) "2012-11-19 15:37:12"
                public updated => NULL
            }
        )
    }
    3 => object stdClass(14) {
        public id => string(1) "4"
        public parent_id => string(1) "0"
        public name => string(11) "Spare parts"
        public uri => string(11) "spare-parts"
        public created => string(19) "2012-11-19 15:16:59"
        public updated => NULL
        public subcategories => array(1) (
            0 => object stdClass(13) {
                public id => string(2) "14"
                public parent_id => string(1) "4"
                public name => string(11) "Consumables"
                public uri => string(11) "consumables"
                public created => string(19) "2012-11-19 15:37:39"
                public updated => NULL
            }
        )
    }
)

And I need to convert it to associative array like this:

array(
    '1' => 'category name',
    '3' => '&nbsp;&nbsp;&nbsp;subcategory name',
    '4' => '&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;subcategory name',
    '2' => 'category2 name',
    '5' => '&nbsp;&nbsp;&nbsp;subcategory2 name',
);

Each subcategory should be indented by spaces. But I'm not really familiar with recursion and need some help, I would really appreciate if you could help me. Thanks in advance.

UPDATE: I've ended up with following:

$options = array();
$this->to_array($tree, $options, '&nbsp;&nbsp;&nbsp;', 0);

function to_array($tree, & $target, $indention = '', $lvl = 0)
{
    foreach($tree as $leaf)
    {
        $target[$leaf->id] = str_repeat($indention, $lvl).$leaf->name;

        if (isset($leaf->subcategories))
        {
            $this->to_array($leaf->subcategories, $target, $indention, $lvl + 1);
        }
    }
}

any suggestions on improvement?

How would you fetch the nth id from the final array if all it's keys are id? — Dale
– Dale, Commented Nov 26, 2012 at 11:30
why you want like that an all the array's are same structure so use for each loop to loop through the data. — Venkata Krishna
– Venkata Krishna, Commented Nov 26, 2012 at 11:32
I don't think you can get it done like this. Each id key will overwrite the previous id key. — web-nomad
– web-nomad, Commented Nov 26, 2012 at 11:33
final array is for example only, instead of 'id' there would be id of the category, I've edited the question — UAMoto
– UAMoto, Commented Nov 26, 2012 at 11:38

jaudette · Accepted Answer · 2012-11-26 12:43:30Z

1

I would go for something along the lines of:

function printArray($arr, &$target, $header = '') {
  foreach($arr as $category) {
    $target[$category->id] = $header . $category->name;
    printArray($category->subcategories, $target, $header . '&nbsp;');
  }
}

// And then, from your source
$targetArray = array();
printArray($source, $targetArray);

That doesn't deal with possible collisions, but if your data is coming from a single table, then collisions should not happen.

To customize even more, you pass the header modification as a parameter to the recursive function like:

function printArray($arr, &$target, $header = '', $headerIncrement = '&nbsp;') {
  foreach($arr as $category) {
    $target[$category->id] = $header . $category->name;
    printArray($category->subcategories, $target, $header . $headerIncrement, $headerIncrement);
  }
}

That would allow you to call it with

printArray($source, $target, '', '&nbsp;&nbsp;&nbsp;');
//or even
printArray($source, $target, '', '<span class="spacer">&nbsp;</span>');

And add styling in your css to change the spacing how you want.

edited Nov 26, 2012 at 12:43

answered Nov 26, 2012 at 12:02

jaudette

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3 Comments

UAMoto Over a year ago

Thank you, you've shown me the light! I've updated question, maybe you could make some improvements to this code?

jaudette Over a year ago

I just update my code, i forgot to update the $header in the recursive call. Now $header will grow with each level. This would add &nbsp to each level. You can change the behavior by changing the recursive call (from $header . '&nbsp' to $header . '  ').

jaudette Over a year ago

@UAMoto by using the header and increment, you are saving a for loop (in the str_repeat) for each call and that loop is not required since you are already in a loop doing the same count.

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