Table: check for missing X only if not sparse
Table: check for missing X only if not sparse

Missing entries in sparse are considered to be 0.

qPCR4vir/orange3,cheral/orange3,cheral/orange3,cheral/orange3,cheral/orange3,qPCR4vir/orange3,qPCR4vir/orange3,qPCR4vir/orange3,qPCR4vir/orange3,qPCR4vir/orange3,cheral/orange3,cheral/orange3