In Seurat's pbmc3k tutorial, they set the CreateSeuratObject with various parameters including `min.cell=3` and `min.features=200`

Can anybody explain exactly what these two parameters mean and where they pull the numbers 3 and 200? 

The [Seurat manual](https://cran.r-project.org/web/packages/Seurat/Seurat.pdf) does a good job explaining the parameters for any function.

> **min.cells** Include features detected in at least this many cells. Will subset the counts matrix as well. To reintroduce excluded
> features, create a new object with a lower cutoff.
> 
> **min.features** Include cells where at least this many features are detected.

The values they picked here are somewhat arbitrary, but `min.cells` helps limit the number of genes used by removing those unlikely to play any part in differentiating groups of cells due to being expressed in very few cells. In general, most genes removed will be those with zero counts across all cells. `min.features` removes dead cells cells and empty droplets where few genes are detected.