How to create partial invoice?

Question

From a specific order I want to create an invoice for some selected items from that order.

I have successfully created an invoice for the whole order programmatically, but I want to create a partial invoice of that order.

Answer 1

Atlast I got it .
Had to dig magento to get this .

$orderid // order id
$order = Mage::getModel('sales/order')->load($orderid);

or for order increment id 
$orderincrmentid // order increment id

$order = Mage::getModel('sales/order')->loadByIncrementId($orderincrmentid);


if($order->canInvoice()) {          
    $invoiceId = Mage::getModel('sales/order_invoice_api')
            ->create($order->getIncrementId(), $itemsarray ,'your_comment' ,1,1);
}
echo $invoiceId; // Gives increment Invoice id

@parameters for above create function :

1st parameter : order increment id

2nd parameter : array

// array format . [Main point]

   foreach($order->getAllItems() as $item) {
$item_id = $item->getItemId(); //order_item_id
$qty = $item->getQtyOrdered();   //qty ordered for that item
}

array('56'=>'3','57'=>'1','58'=>'0');

array([order_item_id] => [qty]); // general array format

So here you will add order item id as key and its qty as its value .
If one do not want to create invoice id a particular item then simply pass value of its quantity as 0 // zero .

3rd parameter : comment

4th parameter : to send mail ----> 1 not send mail ----> 0

5th parameter : include comment in mail ----> 1 not include comment in mail ----> 0

It returns invoice increment id .

Hope it helps someone .