Hi

I'm using plotHeatmap (library(scater)) to visualize the accuracy of cell type annotation output from SingleR. In total I got 28 labels, but as you can see on the top of the plot, the color different is hard to distinguish due to too many labels. I wonder whether there is a simple way to show only 5 to 7 labels in this plot, this is because I only care some specific cell types only, not all of them. For example "AT1 cells, AT2 cells and B cells" are the three cells I'm interested. How to only plot for only three labels?

     Library(scater)  
     plotHeatmap(sce.data.combined.sct, order_columns_by = "labels", features=feature)

![heatmap output ][1]


  [1]: /media/images/40053c91-45c3-473d-aa97-f50c8f7e
Gonna cheat and just recommend [dittoSeq](http://www.bioconductor.org/packages/release/bioc/html/dittoSeq.html). To do what you want will be something like:

```
dittoHeatmap(sce.data.combined.sct, genes = feature, order.by = "labels", annot.by = "labels", 
  cells.use = sce.data.combined.sct$labels %in% c("AT1 cells", "AT2 cells", "B cells"), scale = "none")
```

You may also be interested in setting `scaled.to.max = TRUE`, which is useful for single-cell data given their enrichment for 0s. Setting `scale = "row"` will plots z-scores instead. I also usually pass `complex = TRUE` and `use_raster = TRUE` with single cell data, as it makes the resulting image much easier to edit in Illustrator or such.