Examples with aggregated data from multiple experiments

[jashapiro]

I guess I haven't been thinking about the aggregate cases since none of our examples or planned future examples use the aggregate option.

Originally posted by @cansavvy in #232 (comment)

One of the major features of refine.bio is the ability to aggregate data from multiple experiments into a single downloadable expression matrix. We should have examples that highlight this! Of course, it is something that can be quite fraught with caveats, but that is all the more reason to have a use case that presents reasonable ways handle such data. This might include some batch correction, or maybe just highlighting clustering by platform that might occur.

This issue should be split into specific ideas, but I thought a placeholder was worth filing!