GROUPFILTER <group-name> [FIXEDLEN=<length>][VARLEN=<length>]ITEM=<item-offset> <filter>
where <group-name> is defined here . FIXEDLEN and VARLEN require integer values to define the fixed and variable number of words in the group definition. If omitted they default to zero. <item-offset> is the index of the item in the group, starting from zero, that is being tested and <filter> is:
KEEP | REJECT (<expr>,<expr>)
The GROUPFILTER command removes all the items associated with each member of <group-name> from the current event that do not satify the condition specified by <filter>, eg.
GROUPFILTER CLUST VARLEN 3 ITEM 1 REJECT (0,0)
would remove all members of group CLUST where the 2nd item for each subset of 3 items was zero.