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 satisfy the condition specified by
<filter>
Example
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.