[reference1](https://cran.r-project.org/web/packages/umap/vignettes/umap.html) Uniform Manifold Approximation and Projection (UMAP) is an relatively newly developed ...
adata AnnData with obsm[spatial_key], obsm[umap_key], obs[obs_col]. obs_col Column in adata.obs used for colouring / legend. max_cells Randomly subsample to this many cells for rendering speed.