cann`t change the relation content of GMatrix

[doityth777]

a GMatrix with relation content set by setRation() function already. but i
want to only change the relation name or certain name of attribute. how to do?

[Mike Gashler]

1- call "GMatrix::relation()" to obtain a smart_ptr (see GHolders.h) that
references the relation.

2- call "smart_ptr::get()" to obtain a pointer to the relation (GRelation*).

3- call "GRelation::type()" to make sure that it is ARFF.

4- cast to GArffRelation.

5- call "setName" or "setAttrValueCount", etc. (Hmm, it looks like I have not
provided a "setAttrName" method. Perhaps that should be added.)

Example:

GRelation* pRel = mymatrix.relation().get();

if(pRel->type() != GRelation::ARFF)

ThrowError("Expected a GArffRelation. Got something else.");

GArffRelation pArffRel = (GArffRelation)pRel;

pArffRel->setName("new_name");

(disclaimer: I did not compile this.)

(It seems that my use of smart pointers is what is causing the confusion. It
might help to examine the "smart_ptr" class in GHolders.h, or read about smart
pointers.)