[R]: fix a minor bug in fm.as.vector.
[R]: fix a minor bug in fm.as.vector.

icoming/FlashX,icoming/FlashX,icoming/FlashX,icoming/FlashGraph,zheng-da/FlashX,icoming/FlashGraph,flashxio/FlashX,flashxio/FlashX,icoming/FlashGraph,flashxio/FlashX,icoming/FlashGraph,icoming/FlashX,icoming/FlashX,flashxio/FlashX,zheng-da/FlashX,zheng-da/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashGraph,zheng-da/FlashX,zheng-da/FlashX