Does grouping always happen on the actual field data or can it be down after cellFilter is applied ?
like we can do it in filter and sorting using sortCellFiltered: true, filterCellFiltered: true
http://plnkr.co/edit/eswSZSnEgu620ft9npwy?p=preview
look at the I
column the raw value is a number between 0,4
and a cellfilter
is applied which change the value to true
if value is 0,1,2
and false
other wise. see how grouping is messed up