If this data is coming from DB, then you can use on_data_display filter to replace it.

For e.g. to make some string uppercase on grid display, we can have code like.

$e["on_data_display"] = array("filter_display", null, true)
$grid->set_events($e)

function filter_display($data)
{
/*
These comments are just to show the input param format
Array
(
[params] => Array
(
[0] => Array
(
[client_id] => 1
[name] => Client 1
[gender] => My custom malea
[company] => My custom Client 1 Company 1
)

[1] => Array
(
[client_id] => 2
[name] => Client 2
[gender] => male
[company] => Client 2 Com2pany 11
)

…….
*/
foreach($data["params"] as &$d)
{
$d["gender"] = strtoupper($d["gender"]);
}