How to prevent empty array values in serialization?

[Lionel]

I have six textboxes on a page.

For the db insert I do

PHP Code:

$preddata1 = serialize((is_array($_POST['predminutes1']) ? $_POST['predminutes1']: array())); 


and I insert $preddata1.

Results inserted in db are as below

PHP Code:

 a:6:{s:10:"0000000031";s:2:"25";s:10:"0000000032";s:0:"";s:10:"0000000033";s:2:"35";s:10:"0000000034";s:0:"";s:10:"0000000035";s:0:"";s:10:"0000000036";s:0:"";} 


As you can see the array only has 2 values "25" and "35".

How can I prevent the other empty values to be recorded?