PHP adds to associated array generates new nodes

This is my array:

This is my final array:

$data = [
            'domain'=> $xmlDocument->domain,
            'FirstDate' => $xmlDocument->dateAttribute->first_date,
            'LastDate' => $xmlDocument->dateAttribute->last_date,
            'Category' => $xmlDocument->category->name,
            'Action' => $xmlDocument->websiteAction->name,
            'Source' => $xmlDocument->source->name,
            'LogFile' => $xmlDocument->log_file,
            'DateAttribute' => [
                        'Name' => $xmlDocument->dateAttribute->name,
                        'Place' => $xmlDocument->dateAttribute->dateLocation->name,
                        'DateFunction' => $xmlDocument->dateAttribute->dateFunction->name
                    ],
            'MasterPage' => [
                'MasterAttributes' =>[

                ],
                'Container'=>[
                    'xpath' => $xmlDocument->masterInformation->xpath
                ],
                'NextPage' =>[],
                'LinkAttribute'=>[]
            ],
        ];

as you see, the MasterAttributes key is an empty array and I want to fille it.

What I have tried

$attributes = $xmlDocument->masterInformation->masterAttributes;
foreach($attributes as $attribute) {
    $masterAttribute = [
        'Attribute' => [
            'name' => $attribute->attributeName->name,
            'default_value' => $attribute->default_value
        ]
    ];
    $data['MasterPage'] ['MasterAttributes'][] = $masterAttribute;
}

The generated xml is:

<MasterAttributes>
         <item0>
            <Attribute>
               <name>bathroom</name>
               <default_value>This is the default value</default_value>
            </Attribute>
         </item0>
         <item1>
            <Attribute>
               <name>price</name>
               <default_value>vfd</default_value>
            </Attribute>
         </item1>
         <item2>
            <Attribute>
               <name>bathroom</name>
               <default_value>new default value</default_value>
            </Attribute>
         </item2>
      </MasterAttributes>

please check that there are extract item0, item1, item2

how to remove them please?

Update 1

after the first answer from @lowerends, I got this result

 <MasterAttributes>
         <Attribute_0>
            <name>bathroom</name>
            <default_value>This is the default value</default_value>
         </Attribute_0>
         <Attribute_1>
            <name>price</name>
            <default_value>vfd</default_value>
         </Attribute_1>
         <Attribute_2>
            <name>bathroom</name>
            <default_value>new default value</default_value>
         </Attribute_2>
      </MasterAttributes>

very close to waht I need but I need to have Attribute not Attribute 0 or Attribute 1

Update 2

I generated the xml like this:

$xml = new SimpleXMLElement("<?xml version=\"1.0\"?><websiteInformation></websiteInformation>");
        $this->array_to_xml($data,$xml);
        $xml->asXML("FileName".XmlDocument::find($id)->id.".xml");

where $data is the finall array, and array_to_xml function is:

 public  function array_to_xml($student_info, &$xml_student_info) {
        foreach($student_info as $key => $value) {
            if(is_array($value)) {
                if(!is_numeric($key)){
                    $subnode = $xml_student_info->addChild("$key");
                    $this->array_to_xml($value, $subnode);
                }
                else{
                    $subnode = $xml_student_info->addChild("item$key");
                    $this->array_to_xml($value, $subnode);
                }
            }
            else {
                $xml_student_info->addChild("$key",htmlspecialchars("$value"));
            }
        }
    }

---

You can do this:

$attributes = $xmlDocument->masterInformation->masterAttributes;
foreach($attributes as $key => $attribute) {
    $masterAttribute = [
        'name' => $attribute->attributeName->name,
        'default_value' => $attribute->default_value
    ];
    $data['MasterPage']['MasterAttributes']["Attribute_$key"] = $masterAttribute;
}

This will make sure that you don't have duplicate <Attribute> elements in your <MasterAttributes> element.