A cell's transcript measurements can be represented as a roughly twenty-thousand-dimensional vector of messenger RNA counts, including zeros for transcripts that are absent.

“And to say in a human, maybe it's just something like twenty thousand different types of these, we're splicing many, many more, but they're sort of the, the rough level. So what you de facto have is per cell a twenty thousand dimensional vector that has a whole bunch of zeros when stuff is not there, but then a whole bunch of sort of numbers, how many of these counts of these messenger RNAs you have.”