How to edit particular value in session table?

[eluser]CroNiX[/eluser]

Code:

//Get the key 'search_conditions' data from session
$data = $this->session->userdata('search_conditions');

//Overwrite the value for 'aaa' (should currently be Array ( [aaa] => value1, [bbb] => value2 ))
$data['aaa'] = 'changed_value1';

//store it back in session using 'search_conditions' as the key
$this->session->set_userdata('search_conditions', $data);