title: How to plot multiple UMAPs in a specified grid such as 6 x 3?
body: <p>I am using the new Seurat 3 package to analyze single-cell sequencing data. I have merged 18 Seurat Objects and have saved the individual identifiers in the meta.data. When plotting out the 18 individual UMAPs using the <code>split.by</code> argument in the <code>DimPlot</code> function, it returns a plot in alphabetical order. It also plots 5 UMAPs on the first three rows and 3 on the last. I would like to plot a 6 by 3 grid and be able to order the UMAPs not alphabetically. Below is the command I used.</p>
  <pre><code>DimPlot(object = object, reduction = &quot;umap&quot;, split.by = &quot;orig.ident&quot;)
  </code></pre>