[R]: fix a bug in loading a sparse matrix.
[R]: fix a bug in loading a sparse matrix.

flashxio/FlashX,icoming/FlashX,flashxio/FlashX,flashxio/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashX,icoming/FlashX,icoming/FlashX,flashxio/FlashX,icoming/FlashX